The composition and structure of PIII(plasma immersion ion implantation)carbonitrided Cr4Mo4V steel were analyzed using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),optical microscopy(OM)and SEM.The re...The composition and structure of PIII(plasma immersion ion implantation)carbonitrided Cr4Mo4V steel were analyzed using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),optical microscopy(OM)and SEM.The results indicate that the nitride and carbide are dispersion phase precipitation and except formation of compound other implantation atoms dissolve into martensite matrix.The total concentration of carbon and nitrogen is about 30 at%near the surface,and still keeps at about 20 at%even at the depth of 8μm.The effect of treatment temperature,implantation time and ratio of N2 to CH4 on the hardness and wear resistance of carbonitrided layer are investigated.It is found that the hardness of Cr4Mo4V steel increases after treatment.The highest hardness of samples is 22.3 GPa,which is about 1.8 times than initial steel.The dry-wear resistance of the samples is also improved after treatment,and the sample with higher hardness shows the better wear resistance.展开更多
The plasma electrolytic carbonitriding （PEC/N） on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KC1 in a very short period of time. The microdischarge characteristics of the ...The plasma electrolytic carbonitriding （PEC/N） on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KC1 in a very short period of time. The microdischarge characteristics of the volt- age/current on the Q235 were observed using real-time imaging during the PEC/N. The microstructure and element distribution of the carbonitriding layer were examined using scanning electron microscope （SEM） equipped with energy dispersive spectroscope （EDS）. The effect of microdischarge on roughness, thickness and microhardness was evalua- ted. The formation of the carbonitriding layer was discussed. Research shows that it is similar in the microstructure and properties between the plasma electrolytic carbonitriding and the traditional gas carbonitriding. The formation of the carbonitriding layer results from the carbon and nitrogen fluctuation in PEC/N process. The microhardness and thickness can be up to HV 779 and 0. 360 mm in 180 s, respectively, which is close to the results of the gas carboni- triding in the microhardness. Therefore, the plasma electrolytic carbonit^riding has a potential to substitute the gas carbonitriding.展开更多
The present paper reports the unusual enhancement of endurance life of ball bearings subjected to carbonitriding treatment. The microstructure was characterized by scanning electron microscopy and correlated with hard...The present paper reports the unusual enhancement of endurance life of ball bearings subjected to carbonitriding treatment. The microstructure was characterized by scanning electron microscopy and correlated with hardness and X-ray diffraction analysis. Endurance tests at 90% reliability revealed that the carbonitrided bearings exhibit nearly ten times more life than the non-carbonitrided bearings. This is attributed to synergic combination of retained austenitic, fine martensitic microstructure and ultrafine carbide precipitates obtained by carbonitriding treatment.展开更多
AISI 321 austenitic stainless steel was treated using rf plasma carbonitriding with the intention of use low-cost orthopedic implant material in biomedical applications. The treatment process was carried at low workin...AISI 321 austenitic stainless steel was treated using rf plasma carbonitriding with the intention of use low-cost orthopedic implant material in biomedical applications. The treatment process was carried at low working gas pressure of 0.075 mbar in nitrogen-acetylene gaseous mixture to form a superficial carbonitrided layer. The samples were treated using rf inductively coupled at a fixed plasma-processing power of 500 W and for a processing time varied from 4 to 20 minutes. The microstructural, mechanical and tribological properties of the untreated and treated samples were studied. The surface hardness is improved by rf plasma carbonitriding to a maximum of 1468 HV0.1 for plasma-processing time of 16 min. To evaluate the biocompatibility performance, the blood was cultured in RPMI media to test the adhesion of blood cells on the untreated and treated samples. It has been found that the blood adhesion on the treated samples is enhanced with increasing the plasma-processing time. The contact angle of the carbonitrided surfaces is decreased to lower values compared to that of the untreated surface. Furthermore, the carbonitrided layer in-vitro corrosion was tested in Ringer’s solution. A degradation in the corrosion resistance was observed for the sample carbonitrided at low plasma processing time of 4 min. However, the corrosion resistance increased to a maximum value at a plasma-processing time of 8 min then gradually decreased with further increase of plasma processing time.展开更多
Diamond-like Carbon (DLC) coatings have attracted significant attention due to their low friction coefficient, high degree of hardness, chemical inertness, and high wear resistance as well as and their many possible u...Diamond-like Carbon (DLC) coatings have attracted significant attention due to their low friction coefficient, high degree of hardness, chemical inertness, and high wear resistance as well as and their many possible uses in metallurgical, aeronautical, and biomedical applications. However, DLC has low adhesion strength to metallic substrates. Carbonitriding was performed before DLC deposition to improve this adherence. Different concentration of nitrogen in the gas mixture was used during the carbonitriding of Ti6Al4V alloy. DLC films were subsequently grown from methane using plasma enhanced chemical vapor deposition. The samples were characterized with Raman scattering spectroscopy, nanoindentation, and tribological tests. Films from 80.0% N2 had the best friction coefficient (0.07) and a critical load of ~22 N. In the scratching test, these films had adhesive failure and they completely detached from the substrate only in the end of the tests. SEM images show carbonitring promoted a significant increase in the surface defects (homogeneously distributed) but without the presence of microcracks. EDX analysis indicated that nitrogen element was diffused throughout the thickness of the samples. Hydrogen and carbon atoms from carbonitriding formed a diffusion-barrier layer that can be used as the first step for DLC deposition. This carbonitriding can also provide a carbide layer, which serves as the precursor for the nucleation and growth of DLC films.展开更多
The microstructure, thickness, microhardness and wear resistance of single-boronizing, carbonitriding+boronizing and carbonitriding+RE-boronizing layers of 16Mn steel were investigated respectively. Effect of rare ear...The microstructure, thickness, microhardness and wear resistance of single-boronizing, carbonitriding+boronizing and carbonitriding+RE-boronizing layers of 16Mn steel were investigated respectively. Effect of rare earths on microstructure and properties of the penetrated layer were studied and the mechanism of effects of rare earths was discussed. The result showed that the structure, microhardness, brittleness and wear resistance of the penetrated layer after carbonitriding+ RE-boronizing were better than that of conventional boronizing and carbonitriding, especially the wear resistance of boronized layer was increased remarkably. The RE-boronizing layer of the steel is single phase Fe2B, and RE elements enhanced Fe2B (002) direction texture. The distribution of rare earth element (La) in the layer was non-uniform. RE content is higher between borides than that of the interior of borides. An optimum value of the addition of RE element in the agent was 8%. The average service life of the 16Mn steel brick mould treated by carbonitriding+RE-boronizing was 1.5 times as long as the service life of the mould treated by carbonitriding-boronizing.展开更多
The application of rolling for fabricating grate on titanium stripe has been explored in this paper. Then the mechanically robust Ti（C,N） diffusion layer was synthetized directly on the grates by laser carbonitridin...The application of rolling for fabricating grate on titanium stripe has been explored in this paper. Then the mechanically robust Ti（C,N） diffusion layer was synthetized directly on the grates by laser carbonitriding in the mixture gas of nitrogen and methane. The results shows that the carbonitriding process is accelerated by temperature enhancement with decreasing scanning speed, The Ti（C,N） diffusion layer is kept at 2 ~nn in thickness, when the scanning speed is smaller than 4 mm/s. The contact angle increases from 20~ to 143.6~ by designing an appropriate grate size and surface roughness. Meanwhile, the relationship between hydrophobicity, hardness performance and scanning speed is also discussed. The hardness of diffusion layer increases with decreasing laser scanning speed, and is up to 11.2 GPa. The surface structure and hydrophobic state are maintained after three cycles of sandpaper abrasion, which has improved the robustness of surface grate.展开更多
High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting...High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting.An equivalent austenite diameter was proposed,taking into account the weakening effects of proeutectoid ferrite films and Ti carbonitride precipitation.Based on this,a hot ductility prediction model for the slab was established to investigated hot ductility.The results show that as Ti content increases,the hot ductility of Ti microalloy steel initially increases and then decreases.At low Ti content,the pinning effect of Ti carbonitrides increases with the increase in Ti content,which inhibits grain coarsening for improving hot ductility.As Ti content increases,the size of carbonitrides grows,weakening the pinning effect and leading to austenite grain coarsening.Simultaneously,the formation of Ti carbonitrides inhibits proeutectoid ferrite film formation,leading to a reduction in its thickness.These combined factors reduce the hot ductility of the continuous casting steel.According to the hot ductility prediction model,in order of severity,the factors affecting hot ductility are:proeutectoid ferrite film,chain-like nanoscale Ti carbonitrides,austenite grain size,and dispersed nanoscale Ti carbonitrides.An accuracy error of less than 10%is shown by the model.展开更多
The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence thethermoplasticity,thereby affecting the quality of the slab.In this work,a prediction model...The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence thethermoplasticity,thereby affecting the quality of the slab.In this work,a prediction model for two-stage austenite growth under varyingcooling rates was established by incorporating the effect of second-phase pinning and high-temperature ferrite-austenite phase transform-ation and growth theory.The results indicate that with 0.02wt%Ti,the high-temperature ferrite growth exhibits typical parabolic growthcharacteristics.When the Ti content increases to 0.04wt%,the high-temperature ferrite grain boundary migration rate significantly slowsduring the initial solidification stage.The predicted austenite grain sizes for 0.02wt%Ti microalloyed steel at the center,quarter,and sur-face of the slab are 5592,3529,and 1524μm,respectively.For 0.04wt%Ti microalloyed steel,the austenite grain sizes are 4074,2942,and 1179μm at the same positions.The average error is within 5%.As the Ti content increases from 0.02wt% to 0.04wt%,the austenitegrain refinement at the center is most significant,with an average grain size reduction of 27.14%.展开更多
Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corre...Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corrected from 1 to 2.The correct author affiliation has been provided in this Correction and the original article[1]has been corrected.展开更多
Hafnium carbonitride(HfC_(x)N_(1-x))ceramics have drawn considerable interest due to their exceptional me-chanical and thermophysical properties.Herein,we report a novel single-source precursor with Hf-N bonds as the ...Hafnium carbonitride(HfC_(x)N_(1-x))ceramics have drawn considerable interest due to their exceptional me-chanical and thermophysical properties.Herein,we report a novel single-source precursor with Hf-N bonds as the main chain and fabricate HfC_(x)N_(1-x)ceramics after pyrolysis of the precursor.The synthesis,ceramic conversion,and microstructural evolution of the single-source precursor as well as the derived HfC_(x)N_(1-x)ceramics treated under various atmospheres were investigated.The results indicate that in an argon atmosphere,the nitrogen content within HfC_(x)N_(1-x)decreases with rising temperature.While under a nitrogen atmosphere,the high concentration of N_(2)facilitates the rapid conversion of HfO2 to Hf7O8N4,which subsequently promotes the transformation of the HfC_(x)N_(1-x)solid solution ceramics.During this process,there is also an inhibitory effect of N_(2)on the tendency of HfN into HfC.Moreover,the desired chemical composition of HfC_(x)N_(1-x)can be regulated by adjusting the N_(2)concentration in the heat treat-ment atmosphere.The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfC_(x)N_(1-x)ceramics.展开更多
Invar steels possess excellent thermal expansion properties,making them suitable as materials for manufacturing precision instruments.However,conventional invar steels lack sufficient strength for engineering applicat...Invar steels possess excellent thermal expansion properties,making them suitable as materials for manufacturing precision instruments.However,conventional invar steels lack sufficient strength for engineering applications,and various strengthening methods are urgently needed to enhance their strength.In this work,the possibility of enhancing the strength and maintaining low coefficient of thermal expansion(CTE)of the steel through mechanical heat treatment and the introduction of vanadium carbonitride is demonstrated.V-N microalloying and various heat treatment processes enable invar steel to enhance its strength while maintaining low thermal expansion properties.The strength of low-nitrogen addition invar steel measured 593 MPa during direct aging,representing a 44.6% increase compared to invar steel.After undergoing cold-deformation aging,the strength of low-nitrogen invar steel increased to 790 MPa,indicating a substantial improvement in strength relative to the direct aging condition.Notably,the coefficient of thermal expansion remained at 0.98×10^(-6)℃^(-1).By further increasing N content to introduce more vanadium carbonitride,the strength of high-nitrogen invar steel reached 927 MPa under cold-deformation process while maintaining a low CTE value of 1.02×10^(-6)℃^(-1).This achieved an extraordinary balance of high strength and low CTE,which is due to a well combination of various strengthening mechanisms,especially the Orowan strengthening where dislocations continuously bypass vanadium carbonitride to achieve the strengthening effect.The resulting findings are important for future preparation of excellent properties invar steel in industrial applications.展开更多
The morphology,size,quantity,and composition of complex oxide+carbonitride in H13 steel held at 1250℃for 5,10,and 15 h were determined.The results show that the ratio and number of complex carbonitrides with cores in...The morphology,size,quantity,and composition of complex oxide+carbonitride in H13 steel held at 1250℃for 5,10,and 15 h were determined.The results show that the ratio and number of complex carbonitrides with cores in H13 steel are gradually increased when holding at 1250℃compared with those in the original H13 steel,and the core size increases.There are one or more oxide cores in(Ti_(x),V_(1-x))(Cy,N_(1-y)),including xCaO·zAl_(2)O_(3),xCaO·yMgO·zAl_(2)O_(3),and CaO after holding at 1250℃,in addition to MgO·Al_(2)O_(3)and Al_(2)O_(3)in the original steel.The equilibrium temperature for(Ti_(x),V_(1-x))(Cy,N_(1-y))precipitation at the solidification front and decomposition in the solid state was theoretically analyzed,which was affected by the x value and the product of Ti and N contents in H13 steel.Meanwhile,the composition of(Ti_(x),V_(1-x))(Cy,N_(1-y))is influenced by the oxide cores.It is convinced that(Ti_(x),V_(1-x))(Cy,N_(1-y))with oxide cores has a higher stability,especially for oxides with a high Al_(2)O_(3)content.Heat treatment at high temperature facilitates a more reasonable analysis of oxide+carbonitride,and the generation mechanism of oxide+carbonitride was discussed.展开更多
Carbonitride MXenes,such as Ti_(3)CNT_(x),Ti_(2)C_(0.5)N_(0.5)T_(x),and Ti_(4)(C_(0.2)N_(0.8))_(3)T_(x),have attracted much interest in the large family of two-dimensional(2D)nanomaterials.Like their carbide MXene cou...Carbonitride MXenes,such as Ti_(3)CNT_(x),Ti_(2)C_(0.5)N_(0.5)T_(x),and Ti_(4)(C_(0.2)N_(0.8))_(3)T_(x),have attracted much interest in the large family of two-dimensional(2D)nanomaterials.Like their carbide MXene counterparts,the nanolayered structure and functional groups endow carbonitride MXenes with an attractive combination of physical and chemical properties.More interestingly,the replacement of C by N changes the lattice parameters and electron distribution of carbonitride MXenes due to the greater electronegativity of N as compared to C,thus resulting in significantly enhanced functional properties.This paper reviews the development of carbonitride MXenes,the preparation of 2D carbonitride MXenes,and the current understanding of the microstructure,electronic structure,and functional properties of carbonitride MXenes.In addition,applications,especially in energy storage,sensors,catalysts,electromagnetic wave shielding and absorption,fillers,and environmental and biomedical fields,are summarized.Finally,their current limitations and future opportunities are presented.展开更多
Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum ...Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum carbides or nitrides(MAX) phases,which is environmentally unfriendly.In this work,Ti_(3)AlCN MAX without HFetching was employed directly to observably enhance the kinetics and the cycling stability of MgH_(2).With addition of10 wt% Ti_(3)AlCN,the onset dehydrogenation temperature of MgH2 was dropped from 320 to 205℃,and the rehydrogenation of MgH2 under 6 MPa H2 began at as low as50℃.Furthermore,at 300℃,it could provide 6.2 wt% of hydrogen in 10 min.Upon cycling,the composite underwent an activation process during the initial 40 cycles,with the reversible capacity increased from 4.7 wt% to 6.5 wt%.After that,the capacity showed almost no attenuation for up to 100 cycles.The enhancing effect of Ti_(3)AICN on MgH_(2) was comparable to many MXenes.It was demonstrated that Ti_(3)AICN did not destabilize MgH_(2) but acted as an efficient catalyst for MgH_(2).Ti_(3)AICN was observed to be the active sites for the nucleation and growth of MgH_(2)and might also help in dissociation and recombination of hydrogen molecules.Such two factors are believed to contribute to the improvement of MgH_(2).This study not only provides a promising strategy for improving the hydrogen storage performances of MgH_(2) by using noncorrosive MAX materials,but also adds evidence of nucleation and growth of MgH_(2) on a catalyst.展开更多
Thermo-simulation test and transmission electron microscopy （TEM） have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite ...Thermo-simulation test and transmission electron microscopy （TEM） have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite deformation of C-Ti-Mo steel and C-Nb-Mo steel. The experimental results demonstrated that the austenitic structure was preserved both in C-Ti-Mo steel and C-Nb-Mo steel even if they were relaxed for 1000 s after deformation at 850℃. The strainqnduced precipitate occurs in two kinds of steel. Through the energy spectrum analysis, it was found that the precipitates were Ti（C, N） and Mo-bearing Nb（C, N） respectively and there exists a strong affinity of Mo for Nb with in the precipitates. Mo atoms would enter the lattice of Nb（C, N） particles probably after Nb（C, N） formation.展开更多
Titanium carbonitride (TiCN) coating was prepared on 45# carbon steel by electrical discharge coating (EDC), and the compositions, morphology and microstructure of the coating were studied. In addition, its friction a...Titanium carbonitride (TiCN) coating was prepared on 45# carbon steel by electrical discharge coating (EDC), and the compositions, morphology and microstructure of the coating were studied. In addition, its friction and wear behaviors relative to the physical vapor deposition (PVD) TiN coating were investigated. The results show that the TiCN coating features a thickness of 15μm with a primary phase of TiC 0.3 N 0.7 . The wear rates of the two coatings have no clear distinction at low applied loads. However, severe abrasive wear appears in the PVD TiN coating when the applied load exceeds 30 N, while the TiCN coating features better wear resistance. The abrasive wear with coating peelings is found to be the predominant wear mechanism at high applied loads.展开更多
Based on mass balance and solubility product equations, a thermodynamic model enabling the calcula- tion of equilibrium carbonitride composition and relative amounts as a function of steel composition and tem- peratur...Based on mass balance and solubility product equations, a thermodynamic model enabling the calcula- tion of equilibrium carbonitride composition and relative amounts as a function of steel composition and tem- perature was developed, which provides a method to es- timate the carbonitride complete dissolution temperature for different steel compositions. Actual carbonitride pre- cipitation behavior was further verified in Ti-V-C-N microalloyed steel system. The model suggests that for higher IV] and [Ti] dissolved in steels, it is available to decrease the addition of C and N during alloy composi- tion design. The resultant longer fatigue life of the modified steel could be attributed to the more [V] and [Ti] dissolved in the matrix, inducing finer dispersion of carbonitrides. Therefore, this model is proved to be effective in determining better chemical composition for high-performance steels, leading to possible reductions in the cost of production and improvements in the combined mechanical properties of the steels.展开更多
Using TEM （transmisson electron microscopy）, electron diffraction, EDX （energy dispersive X-ray） analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical compo...Using TEM （transmisson electron microscopy）, electron diffraction, EDX （energy dispersive X-ray） analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical composition of precipitates in the microstructure of high strength Nb-microalloyed Xl00 pipeline steel were investigated, and the strengthening effect of precipitation was quantitatively calculated with Ashhy-Orowan correction model. The precipitates obtained in X100 pipeline steel can be divided into two kinds： ＂complex＂ and ＂single＂ particles by morphology. The EDX analysis of ＂single＂ precipitates reveals that the chemical composition matches well with particle dimensions, especially the Nb to Ti ratio regularly decreases with the increase of particle size. The yield strength increments in the way of precipitation strengthening of X100 pipeline steel reached about 52 MPa, suggesting that the precipitation strengthening is not the dominative strengthening mechanism for X100 pipeline steel.展开更多
Niobium, as the most effective second-phase forming element, was added in the Fe-Crl3-C-N hard- facing alloy to get carbonitride precipitates. Morphology and composition of carbonitride in the hardfacing alloy were st...Niobium, as the most effective second-phase forming element, was added in the Fe-Crl3-C-N hard- facing alloy to get carbonitride precipitates. Morphology and composition of carbonitride in the hardfacing alloy were studied by optical microscopy, scanning electron microscopy, and electron probe microanalyzer. The ther- modynamics and the effect on the matrix of the formation of carbonitride were also discussed. It was found that niobium carbonitrides are complex Nb（C, N） precipitate distributed on grain boundary and matrix of the hardfacing alloy. Under as-welded condition, primary carbonitride particles were readily precipitated from the hardfacing alloy with large size and morphology as they were formed already during solidification. Under heat treatment condi- tion, a large number of secondary carbonitrides can pre- cipitate out with very fine size and make a great secondary hardening effect on the matrix. As a result, addition of niobium in the hardfacing alloy can prevent the formation of chromium-rich phase on grain boundaries and inter- granular chromium depletion.展开更多
基金supported by NSFC(51001039)National Basic Research Program of China(No.2007CB607602)+1 种基金The Program of Excellent Teams of Harbin Institute of TechnologyScience Found for Distinguished Yong Schoolars of Heilongjiang Province(JC200901)
文摘The composition and structure of PIII(plasma immersion ion implantation)carbonitrided Cr4Mo4V steel were analyzed using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),optical microscopy(OM)and SEM.The results indicate that the nitride and carbide are dispersion phase precipitation and except formation of compound other implantation atoms dissolve into martensite matrix.The total concentration of carbon and nitrogen is about 30 at%near the surface,and still keeps at about 20 at%even at the depth of 8μm.The effect of treatment temperature,implantation time and ratio of N2 to CH4 on the hardness and wear resistance of carbonitrided layer are investigated.It is found that the hardness of Cr4Mo4V steel increases after treatment.The highest hardness of samples is 22.3 GPa,which is about 1.8 times than initial steel.The dry-wear resistance of the samples is also improved after treatment,and the sample with higher hardness shows the better wear resistance.
基金Item Sponsored by National Natural Science Foundation of China(50901031)Fundamental Research Funds for Central Universities of China(2012B07414)
文摘The plasma electrolytic carbonitriding （PEC/N） on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KC1 in a very short period of time. The microdischarge characteristics of the volt- age/current on the Q235 were observed using real-time imaging during the PEC/N. The microstructure and element distribution of the carbonitriding layer were examined using scanning electron microscope （SEM） equipped with energy dispersive spectroscope （EDS）. The effect of microdischarge on roughness, thickness and microhardness was evalua- ted. The formation of the carbonitriding layer was discussed. Research shows that it is similar in the microstructure and properties between the plasma electrolytic carbonitriding and the traditional gas carbonitriding. The formation of the carbonitriding layer results from the carbon and nitrogen fluctuation in PEC/N process. The microhardness and thickness can be up to HV 779 and 0. 360 mm in 180 s, respectively, which is close to the results of the gas carboni- triding in the microhardness. Therefore, the plasma electrolytic carbonit^riding has a potential to substitute the gas carbonitriding.
文摘The present paper reports the unusual enhancement of endurance life of ball bearings subjected to carbonitriding treatment. The microstructure was characterized by scanning electron microscopy and correlated with hardness and X-ray diffraction analysis. Endurance tests at 90% reliability revealed that the carbonitrided bearings exhibit nearly ten times more life than the non-carbonitrided bearings. This is attributed to synergic combination of retained austenitic, fine martensitic microstructure and ultrafine carbide precipitates obtained by carbonitriding treatment.
文摘AISI 321 austenitic stainless steel was treated using rf plasma carbonitriding with the intention of use low-cost orthopedic implant material in biomedical applications. The treatment process was carried at low working gas pressure of 0.075 mbar in nitrogen-acetylene gaseous mixture to form a superficial carbonitrided layer. The samples were treated using rf inductively coupled at a fixed plasma-processing power of 500 W and for a processing time varied from 4 to 20 minutes. The microstructural, mechanical and tribological properties of the untreated and treated samples were studied. The surface hardness is improved by rf plasma carbonitriding to a maximum of 1468 HV0.1 for plasma-processing time of 16 min. To evaluate the biocompatibility performance, the blood was cultured in RPMI media to test the adhesion of blood cells on the untreated and treated samples. It has been found that the blood adhesion on the treated samples is enhanced with increasing the plasma-processing time. The contact angle of the carbonitrided surfaces is decreased to lower values compared to that of the untreated surface. Furthermore, the carbonitrided layer in-vitro corrosion was tested in Ringer’s solution. A degradation in the corrosion resistance was observed for the sample carbonitrided at low plasma processing time of 4 min. However, the corrosion resistance increased to a maximum value at a plasma-processing time of 8 min then gradually decreased with further increase of plasma processing time.
基金The authors are very grateful to Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo(FAPESP)for the financial support.
文摘Diamond-like Carbon (DLC) coatings have attracted significant attention due to their low friction coefficient, high degree of hardness, chemical inertness, and high wear resistance as well as and their many possible uses in metallurgical, aeronautical, and biomedical applications. However, DLC has low adhesion strength to metallic substrates. Carbonitriding was performed before DLC deposition to improve this adherence. Different concentration of nitrogen in the gas mixture was used during the carbonitriding of Ti6Al4V alloy. DLC films were subsequently grown from methane using plasma enhanced chemical vapor deposition. The samples were characterized with Raman scattering spectroscopy, nanoindentation, and tribological tests. Films from 80.0% N2 had the best friction coefficient (0.07) and a critical load of ~22 N. In the scratching test, these films had adhesive failure and they completely detached from the substrate only in the end of the tests. SEM images show carbonitring promoted a significant increase in the surface defects (homogeneously distributed) but without the presence of microcracks. EDX analysis indicated that nitrogen element was diffused throughout the thickness of the samples. Hydrogen and carbon atoms from carbonitriding formed a diffusion-barrier layer that can be used as the first step for DLC deposition. This carbonitriding can also provide a carbide layer, which serves as the precursor for the nucleation and growth of DLC films.
基金the Natural Science Foundation of Chongqing (2006BB4391)
文摘The microstructure, thickness, microhardness and wear resistance of single-boronizing, carbonitriding+boronizing and carbonitriding+RE-boronizing layers of 16Mn steel were investigated respectively. Effect of rare earths on microstructure and properties of the penetrated layer were studied and the mechanism of effects of rare earths was discussed. The result showed that the structure, microhardness, brittleness and wear resistance of the penetrated layer after carbonitriding+ RE-boronizing were better than that of conventional boronizing and carbonitriding, especially the wear resistance of boronized layer was increased remarkably. The RE-boronizing layer of the steel is single phase Fe2B, and RE elements enhanced Fe2B (002) direction texture. The distribution of rare earth element (La) in the layer was non-uniform. RE content is higher between borides than that of the interior of borides. An optimum value of the addition of RE element in the agent was 8%. The average service life of the 16Mn steel brick mould treated by carbonitriding+RE-boronizing was 1.5 times as long as the service life of the mould treated by carbonitriding-boronizing.
文摘The application of rolling for fabricating grate on titanium stripe has been explored in this paper. Then the mechanically robust Ti（C,N） diffusion layer was synthetized directly on the grates by laser carbonitriding in the mixture gas of nitrogen and methane. The results shows that the carbonitriding process is accelerated by temperature enhancement with decreasing scanning speed, The Ti（C,N） diffusion layer is kept at 2 ~nn in thickness, when the scanning speed is smaller than 4 mm/s. The contact angle increases from 20~ to 143.6~ by designing an appropriate grate size and surface roughness. Meanwhile, the relationship between hydrophobicity, hardness performance and scanning speed is also discussed. The hardness of diffusion layer increases with decreasing laser scanning speed, and is up to 11.2 GPa. The surface structure and hydrophobic state are maintained after three cycles of sandpaper abrasion, which has improved the robustness of surface grate.
基金financially supported by the National Natural Science Foundation of China(No.51974078)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project,Nos.2022 JH25/10200003 and 2023 JH2/101800058)the Fundamental Research Funds for the Central Universities(No.N25YJS003).
文摘High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting.An equivalent austenite diameter was proposed,taking into account the weakening effects of proeutectoid ferrite films and Ti carbonitride precipitation.Based on this,a hot ductility prediction model for the slab was established to investigated hot ductility.The results show that as Ti content increases,the hot ductility of Ti microalloy steel initially increases and then decreases.At low Ti content,the pinning effect of Ti carbonitrides increases with the increase in Ti content,which inhibits grain coarsening for improving hot ductility.As Ti content increases,the size of carbonitrides grows,weakening the pinning effect and leading to austenite grain coarsening.Simultaneously,the formation of Ti carbonitrides inhibits proeutectoid ferrite film formation,leading to a reduction in its thickness.These combined factors reduce the hot ductility of the continuous casting steel.According to the hot ductility prediction model,in order of severity,the factors affecting hot ductility are:proeutectoid ferrite film,chain-like nanoscale Ti carbonitrides,austenite grain size,and dispersed nanoscale Ti carbonitrides.An accuracy error of less than 10%is shown by the model.
基金financially supported by the National Natural Science Foundation of China(No.52474355)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project,Nos.2022JH25/10200003 and 2023JH2/101800058)the Fundamental Research Funds for the Central Universities(Nos.N25YJS003 and N25DCG006)。
文摘The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence thethermoplasticity,thereby affecting the quality of the slab.In this work,a prediction model for two-stage austenite growth under varyingcooling rates was established by incorporating the effect of second-phase pinning and high-temperature ferrite-austenite phase transform-ation and growth theory.The results indicate that with 0.02wt%Ti,the high-temperature ferrite growth exhibits typical parabolic growthcharacteristics.When the Ti content increases to 0.04wt%,the high-temperature ferrite grain boundary migration rate significantly slowsduring the initial solidification stage.The predicted austenite grain sizes for 0.02wt%Ti microalloyed steel at the center,quarter,and sur-face of the slab are 5592,3529,and 1524μm,respectively.For 0.04wt%Ti microalloyed steel,the austenite grain sizes are 4074,2942,and 1179μm at the same positions.The average error is within 5%.As the Ti content increases from 0.02wt% to 0.04wt%,the austenitegrain refinement at the center is most significant,with an average grain size reduction of 27.14%.
文摘Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corrected from 1 to 2.The correct author affiliation has been provided in this Correction and the original article[1]has been corrected.
基金supported by the National Key R&D Program of China(Grant No.2021YFA0715803)the National Natural Science Foundation of China(Grant Nos.52293373 and 52130205)+3 种基金the Special Funds of the National Natural Science Foun-dation of China(Grant No.52342207)the National Science and Technology Major Project(Grant No.J2022-VI-0011-0042)the Joint Fund of Henan Province Science and Technology R&D Program(Grant No.225200810002)the Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory(Grant No.JCKYS2024607001-1).
文摘Hafnium carbonitride(HfC_(x)N_(1-x))ceramics have drawn considerable interest due to their exceptional me-chanical and thermophysical properties.Herein,we report a novel single-source precursor with Hf-N bonds as the main chain and fabricate HfC_(x)N_(1-x)ceramics after pyrolysis of the precursor.The synthesis,ceramic conversion,and microstructural evolution of the single-source precursor as well as the derived HfC_(x)N_(1-x)ceramics treated under various atmospheres were investigated.The results indicate that in an argon atmosphere,the nitrogen content within HfC_(x)N_(1-x)decreases with rising temperature.While under a nitrogen atmosphere,the high concentration of N_(2)facilitates the rapid conversion of HfO2 to Hf7O8N4,which subsequently promotes the transformation of the HfC_(x)N_(1-x)solid solution ceramics.During this process,there is also an inhibitory effect of N_(2)on the tendency of HfN into HfC.Moreover,the desired chemical composition of HfC_(x)N_(1-x)can be regulated by adjusting the N_(2)concentration in the heat treat-ment atmosphere.The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfC_(x)N_(1-x)ceramics.
基金supported by the Shanxi Provincial Basic Research Program(No.202403021221046)the National Natural Science Foundation of China(Nos.52004180 and 52204350)+5 种基金the China Postdoctoral Science Foundation(No.2020M683706XB)the Research Project Supported by Shanxi Scholarship Council of China(No.2023-080)the Fund Projects for the Central Government to Guide the Development of Local Science and Technology(No.236Z1023G)the Hebei Province High-level Talent Funding Project(No.B20231016)the National College Student Innovation and Entrepreneurship Training Program(No.202410112116)the Graduate Student Scientific Research Innovation Program(No.2024KY278).
文摘Invar steels possess excellent thermal expansion properties,making them suitable as materials for manufacturing precision instruments.However,conventional invar steels lack sufficient strength for engineering applications,and various strengthening methods are urgently needed to enhance their strength.In this work,the possibility of enhancing the strength and maintaining low coefficient of thermal expansion(CTE)of the steel through mechanical heat treatment and the introduction of vanadium carbonitride is demonstrated.V-N microalloying and various heat treatment processes enable invar steel to enhance its strength while maintaining low thermal expansion properties.The strength of low-nitrogen addition invar steel measured 593 MPa during direct aging,representing a 44.6% increase compared to invar steel.After undergoing cold-deformation aging,the strength of low-nitrogen invar steel increased to 790 MPa,indicating a substantial improvement in strength relative to the direct aging condition.Notably,the coefficient of thermal expansion remained at 0.98×10^(-6)℃^(-1).By further increasing N content to introduce more vanadium carbonitride,the strength of high-nitrogen invar steel reached 927 MPa under cold-deformation process while maintaining a low CTE value of 1.02×10^(-6)℃^(-1).This achieved an extraordinary balance of high strength and low CTE,which is due to a well combination of various strengthening mechanisms,especially the Orowan strengthening where dislocations continuously bypass vanadium carbonitride to achieve the strengthening effect.The resulting findings are important for future preparation of excellent properties invar steel in industrial applications.
基金This work is financially supported by Hebei Natural Science Foundation under Grant Nos.E2020402067,E2018402098,and E2021402056,Open Program of State Key Laboratory of Advanced Metallurgy under Grant No.K1:21-08Key Project of Handan Scientific Research Program under Grant No.21122015004the Science and Technology Research and Development Program of Handan City under Grant No.21422101235.The authors would like to express their sincere thanks to Tianjin CISRI-HARDER Materials&Technology Co.,Ltd.for the experiment.
文摘The morphology,size,quantity,and composition of complex oxide+carbonitride in H13 steel held at 1250℃for 5,10,and 15 h were determined.The results show that the ratio and number of complex carbonitrides with cores in H13 steel are gradually increased when holding at 1250℃compared with those in the original H13 steel,and the core size increases.There are one or more oxide cores in(Ti_(x),V_(1-x))(Cy,N_(1-y)),including xCaO·zAl_(2)O_(3),xCaO·yMgO·zAl_(2)O_(3),and CaO after holding at 1250℃,in addition to MgO·Al_(2)O_(3)and Al_(2)O_(3)in the original steel.The equilibrium temperature for(Ti_(x),V_(1-x))(Cy,N_(1-y))precipitation at the solidification front and decomposition in the solid state was theoretically analyzed,which was affected by the x value and the product of Ti and N contents in H13 steel.Meanwhile,the composition of(Ti_(x),V_(1-x))(Cy,N_(1-y))is influenced by the oxide cores.It is convinced that(Ti_(x),V_(1-x))(Cy,N_(1-y))with oxide cores has a higher stability,especially for oxides with a high Al_(2)O_(3)content.Heat treatment at high temperature facilitates a more reasonable analysis of oxide+carbonitride,and the generation mechanism of oxide+carbonitride was discussed.
基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:2023YJS061,2023JBZY019。
文摘Carbonitride MXenes,such as Ti_(3)CNT_(x),Ti_(2)C_(0.5)N_(0.5)T_(x),and Ti_(4)(C_(0.2)N_(0.8))_(3)T_(x),have attracted much interest in the large family of two-dimensional(2D)nanomaterials.Like their carbide MXene counterparts,the nanolayered structure and functional groups endow carbonitride MXenes with an attractive combination of physical and chemical properties.More interestingly,the replacement of C by N changes the lattice parameters and electron distribution of carbonitride MXenes due to the greater electronegativity of N as compared to C,thus resulting in significantly enhanced functional properties.This paper reviews the development of carbonitride MXenes,the preparation of 2D carbonitride MXenes,and the current understanding of the microstructure,electronic structure,and functional properties of carbonitride MXenes.In addition,applications,especially in energy storage,sensors,catalysts,electromagnetic wave shielding and absorption,fillers,and environmental and biomedical fields,are summarized.Finally,their current limitations and future opportunities are presented.
基金financially supported by the Science and Technology Department of Guangxi Zhuang Autonomous (No.GuiKeAD21238022)the Natural Science Foundation of Guangxi Province (No.2019GXNSFBA185004)National Natural Science Foundation of China (Nos.52001079,51961005 and 52261038)。
文摘Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum carbides or nitrides(MAX) phases,which is environmentally unfriendly.In this work,Ti_(3)AlCN MAX without HFetching was employed directly to observably enhance the kinetics and the cycling stability of MgH_(2).With addition of10 wt% Ti_(3)AlCN,the onset dehydrogenation temperature of MgH2 was dropped from 320 to 205℃,and the rehydrogenation of MgH2 under 6 MPa H2 began at as low as50℃.Furthermore,at 300℃,it could provide 6.2 wt% of hydrogen in 10 min.Upon cycling,the composite underwent an activation process during the initial 40 cycles,with the reversible capacity increased from 4.7 wt% to 6.5 wt%.After that,the capacity showed almost no attenuation for up to 100 cycles.The enhancing effect of Ti_(3)AICN on MgH_(2) was comparable to many MXenes.It was demonstrated that Ti_(3)AICN did not destabilize MgH_(2) but acted as an efficient catalyst for MgH_(2).Ti_(3)AICN was observed to be the active sites for the nucleation and growth of MgH_(2)and might also help in dissociation and recombination of hydrogen molecules.Such two factors are believed to contribute to the improvement of MgH_(2).This study not only provides a promising strategy for improving the hydrogen storage performances of MgH_(2) by using noncorrosive MAX materials,but also adds evidence of nucleation and growth of MgH_(2) on a catalyst.
基金Item Sponsored by Natural Science Foundation of Hebei Province of China (E2008001141)
文摘Thermo-simulation test and transmission electron microscopy （TEM） have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite deformation of C-Ti-Mo steel and C-Nb-Mo steel. The experimental results demonstrated that the austenitic structure was preserved both in C-Ti-Mo steel and C-Nb-Mo steel even if they were relaxed for 1000 s after deformation at 850℃. The strainqnduced precipitate occurs in two kinds of steel. Through the energy spectrum analysis, it was found that the precipitates were Ti（C, N） and Mo-bearing Nb（C, N） respectively and there exists a strong affinity of Mo for Nb with in the precipitates. Mo atoms would enter the lattice of Nb（C, N） particles probably after Nb（C, N） formation.
基金Project(51075075)supported by the National Natural Science Foundation of China
文摘Titanium carbonitride (TiCN) coating was prepared on 45# carbon steel by electrical discharge coating (EDC), and the compositions, morphology and microstructure of the coating were studied. In addition, its friction and wear behaviors relative to the physical vapor deposition (PVD) TiN coating were investigated. The results show that the TiCN coating features a thickness of 15μm with a primary phase of TiC 0.3 N 0.7 . The wear rates of the two coatings have no clear distinction at low applied loads. However, severe abrasive wear appears in the PVD TiN coating when the applied load exceeds 30 N, while the TiCN coating features better wear resistance. The abrasive wear with coating peelings is found to be the predominant wear mechanism at high applied loads.
基金financially supported by the Science and Technology Support Project of Jiangxi Province(No. 20112BBE50006)Young Scientists of Jiangxi Province Training Objects(No.20133BCB23032)
文摘Based on mass balance and solubility product equations, a thermodynamic model enabling the calcula- tion of equilibrium carbonitride composition and relative amounts as a function of steel composition and tem- perature was developed, which provides a method to es- timate the carbonitride complete dissolution temperature for different steel compositions. Actual carbonitride pre- cipitation behavior was further verified in Ti-V-C-N microalloyed steel system. The model suggests that for higher IV] and [Ti] dissolved in steels, it is available to decrease the addition of C and N during alloy composi- tion design. The resultant longer fatigue life of the modified steel could be attributed to the more [V] and [Ti] dissolved in the matrix, inducing finer dispersion of carbonitrides. Therefore, this model is proved to be effective in determining better chemical composition for high-performance steels, leading to possible reductions in the cost of production and improvements in the combined mechanical properties of the steels.
文摘Using TEM （transmisson electron microscopy）, electron diffraction, EDX （energy dispersive X-ray） analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical composition of precipitates in the microstructure of high strength Nb-microalloyed Xl00 pipeline steel were investigated, and the strengthening effect of precipitation was quantitatively calculated with Ashhy-Orowan correction model. The precipitates obtained in X100 pipeline steel can be divided into two kinds： ＂complex＂ and ＂single＂ particles by morphology. The EDX analysis of ＂single＂ precipitates reveals that the chemical composition matches well with particle dimensions, especially the Nb to Ti ratio regularly decreases with the increase of particle size. The yield strength increments in the way of precipitation strengthening of X100 pipeline steel reached about 52 MPa, suggesting that the precipitation strengthening is not the dominative strengthening mechanism for X100 pipeline steel.
基金financially supported by the National Natural Science Foundation of China(No.51101050)Natural Science Foundation of Jiangsu Province of China(No.BK2011257)
文摘Niobium, as the most effective second-phase forming element, was added in the Fe-Crl3-C-N hard- facing alloy to get carbonitride precipitates. Morphology and composition of carbonitride in the hardfacing alloy were studied by optical microscopy, scanning electron microscopy, and electron probe microanalyzer. The ther- modynamics and the effect on the matrix of the formation of carbonitride were also discussed. It was found that niobium carbonitrides are complex Nb（C, N） precipitate distributed on grain boundary and matrix of the hardfacing alloy. Under as-welded condition, primary carbonitride particles were readily precipitated from the hardfacing alloy with large size and morphology as they were formed already during solidification. Under heat treatment condi- tion, a large number of secondary carbonitrides can pre- cipitate out with very fine size and make a great secondary hardening effect on the matrix. As a result, addition of niobium in the hardfacing alloy can prevent the formation of chromium-rich phase on grain boundaries and inter- granular chromium depletion.
