According to the oxidation intensity of ore-hosting sandstone, the interlayer oxidation zone of the Shihongtan sandstone-type uranium deposit in the Turpan-Hami basin can be divided into 4 geochemical subzones, namely...According to the oxidation intensity of ore-hosting sandstone, the interlayer oxidation zone of the Shihongtan sandstone-type uranium deposit in the Turpan-Hami basin can be divided into 4 geochemical subzones, namely, intenselyoxidized, weakly-oxidized, redox and unoxidized primary subzones. The elemental geochemical characteristics of the four subzones have been studied in detail, and the results show that U, together with other elements such as Re, Mo, Se, Sr, S, REE, Corganic etc., is enriched in the redox subzone. Re and U have similar geochemical properties in the reductionoxidation process. The geochemical properties of Mo and Se are similar to those of U in the reduction condition, but different from those of U in the oxidation condition. It is proposed that the ore-hosting layers can provide a curtain mount of uranium for uranium mineralization.展开更多
Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be di...Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.展开更多
This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two exp...This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.展开更多
In the creep fatigue crack growth of GH4169 alloy,oxidation is a prominent damage source,which is mainly manifested as the oxidation damage zone in front of crack tip.In order to investigate the property of the oxidat...In the creep fatigue crack growth of GH4169 alloy,oxidation is a prominent damage source,which is mainly manifested as the oxidation damage zone in front of crack tip.In order to investigate the property of the oxidation damage zone formed in the creep fatigue crack growth,crack growth tests of directly aged GH4169 alloy were conducted at 650℃ in air under various load conditions.Interrupted tests were performed to observe the damage characteristics at crack tip.Block tests were systematically executed to quantify the dependency of oxidation damage zone size on load and holding time.The crack propagation of the GH4169 alloy has a close relationship with grain boundary oxidation at 650℃.An oxidation damage zone in front of crack tip includes intergranular microcracks and oxidised but uncracked grain boundaries.Its size has been calculated from transient crack growth rate and described as a function of maximum stress intensity factor and holding time.Based on oxidation damage zone size,a novel model has been developed to predict the creep fatigue crack growth rate of the GH4169 alloy at 650℃.展开更多
The Sain Us gold deposit is a typical auriferous sulphide quartz vein deposit in the InnerMongolian arid steppe climatic region. The oxidation zone has been controlled by the arid cli-mate since the beginning of the H...The Sain Us gold deposit is a typical auriferous sulphide quartz vein deposit in the InnerMongolian arid steppe climatic region. The oxidation zone has been controlled by the arid cli-mate since the beginning of the Holocene. Gold supergene evolution is characterized by enlarge-ment of gold grains, complication of the gold form, raising of the gold grade and increase of thegold fineness; besides, gold and silver have two enrichment peaks at the same depth, which is insharp contrast to the unimodal enrichment of gold and silver and the occurrence of gold aboveand silver below in a humid climatic region. Sun pumping is the main cause for the bimodalenrichment of gold and silver. Illite 2 M_1 is one of the main causes for the upper enrichment peakof gold and silver.展开更多
On the basis of heat transfer and chemical kinetics theory, both connections coal self ignite with oxygen concentration and range of oxidation zone with air leak intensity are analyzed, and calculating method is deduc...On the basis of heat transfer and chemical kinetics theory, both connections coal self ignite with oxygen concentration and range of oxidation zone with air leak intensity are analyzed, and calculating method is deduced to gain the lower limit of oxygen concentration and the range of oxidation zone. The change rule of correlative parameter is quantitatively researched between before nitrogen injection and after nitrogen injection in gob, such as oxygen concentration, oxidation zone width, etc. According to theoretical calculation, the relation position and flow of nitrogen injection with oxidation zone width is conformed, and computational formulas of the best flow and position of nitrogen injection are obtained. It offers a theoretic criterion for preventing and controlling float coal self ignite by nitrogen injection in gob.展开更多
The oxidation behavior of Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys at 800 °C for exposure time up to 100 h was examined. It is shown that oxidation rate of experimental alloys obeys the parabolic kinetics. Ti?22Al...The oxidation behavior of Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys at 800 °C for exposure time up to 100 h was examined. It is shown that oxidation rate of experimental alloys obeys the parabolic kinetics. Ti?22Al?26Nb?1Zr alloy demonstrates more excellent oxidation resistance than the other two alloys. The main oxidation products are TiO2, Al2O3 and AlNbO4 phases for all these alloys. For the Ti?22Al?26Nb?1Zr alloy, Zr addition can modify the growth mechanism of oxide scale, which can effectively hinder the diffusion of oxygen. Whereas, reaction of Zr with oxygen leads to the formation of ZrO2 precipitates for the Ti?22Al?21Nb?6Zr alloy, which promotes the oxygen ingress into the substrate. Meanwhile, oxidation affected zones, including internal-oxidation layer and oxygen-enriched zone, are present beneath the outmost oxide scale. The difference in these zones is derived from the phase constitution in the starting Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys.展开更多
The spatial distribution and diversity of archaeal and bacterial ammonia oxidizers （AOA and AOB） were evaluated targeting amoA genes in the gradient of a littoral buffer zone which has been identified as a hot spot ...The spatial distribution and diversity of archaeal and bacterial ammonia oxidizers （AOA and AOB） were evaluated targeting amoA genes in the gradient of a littoral buffer zone which has been identified as a hot spot for N cycling. Here we found high spatial heterogeneity in the nitrification rate and abundance of ammonia oxidizers in the five sampling sites. The bacterial amoA gene was numerically dominant in most of the surface soil but decreased dramatically in deep layers. Higher nitrification potentials were detected in two sites near the land/water interface at 4.4–6.1 μg NO2-N/（g dry weight soil·hr）, while only 1.0–1.7 μg NO2-N/（g dry weight soil·hr） was measured at other sites. The potential nitrification rates were proportional to the amoA gene abundance for AOB, but with no significant correlation with AOA. The NH4＋ concentration was the most determinative parameter for the abundance of AOB and potential nitrification rates in this study. Higher richness in the surface layer was found in the analysis of biodiversity. Phylogenetic analysis revealed that most of the bacterial amoA sequences in surface soil were affiliated with the genus of Nitrosopira while the archaeal sequences were almost equally affiliated with Candidatus ‘Nitrososphaera gargensis’ and Candidatus ‘Nitrosocaldus yellowstonii’. The spatial distribution of AOA and AOB indicated that bacteria may play a more important role in nitrification in the littoral buffer zone of a N-rich lake.展开更多
Excellent Heat Affected Zone Toughness Technology Improved by use of Strong Deoxidizers(ETISD Technology)has been developed by Baosteel.When deoxidation of molten steel is conducted at the precisely controlled oxygen ...Excellent Heat Affected Zone Toughness Technology Improved by use of Strong Deoxidizers(ETISD Technology)has been developed by Baosteel.When deoxidation of molten steel is conducted at the precisely controlled oxygen concentrations,the formation of the micro-meter inclusions and the nano-meter precipitates in the steel plate can be effectively controlled.During the welding process with high-heat input,the formation of acicular ferrite can be selectively promoted with the aid of micro-meter inclusions;the growth ofγgrain can also be selectively restrained by the pinning effect of nano-meter precipitates.After welding with high-heat input of 400 kJ/cm,excellent heat affected zone toughness can be obtained for the steel plates with both of the above microstructures,and the average absorbed energy is greater than 200 J for V notch Charpy impact test at-20℃.展开更多
A low-diffusion Ni Re Pt Al coating((Ni,Pt)Al outer layer in addition to a Re-rich diffusion barrier layer)was prepared on a Ni_(3)Al-base single crystal(SC)superalloy via electroplating and gaseous aluminizing treatm...A low-diffusion Ni Re Pt Al coating((Ni,Pt)Al outer layer in addition to a Re-rich diffusion barrier layer)was prepared on a Ni_(3)Al-base single crystal(SC)superalloy via electroplating and gaseous aluminizing treatments,wherein the electroplating procedures consisted of the composite deposition of Ni-Re followed by electroplating of Pt.In order to perform a comparison with conventional Ni Al and(Ni,Pt)Al coatings,the cyclic oxidation performance of the Ni Re Pt Al coating was evaluated at 1100 and 1150℃.We observed that the oxidation resistance of the Ni Re Pt Al coating was significantly improved by the greater presence of the residualβ-Ni Al phase in the outer layer and the lesser outward-diffusion of Mo from the substrate.In addition,the coating with the Re-rich diffusion barrier demonstrated a lower extent of interdiffusion into the substrate,where the thickness of the second reaction zone(SRZ)in the substrate alloy decreased by 25%.The mechanisms responsible for improving the oxidation resistance and decreasing the extent of SRZ formation are discussed,in which a particular attention is paid to the inhibition of the outward diffusion of Mo by the Re-based diffusion barrier.展开更多
Excellent heat affected zone(HAZ)toughness technology improved by strong deoxidizers(ETISI)technology has been developed by Baosteel.In the deoxidation process of molten steel by adding strong deoxidizers,the formatio...Excellent heat affected zone(HAZ)toughness technology improved by strong deoxidizers(ETISI)technology has been developed by Baosteel.In the deoxidation process of molten steel by adding strong deoxidizers,the formation of micrometer inclusions and nano-meter precipitates in steel plates can be effectively controlled by a precise control of oxygen concentration.In the welding process with a high-heat input,the formation of acicular ferrite can be selectively promoted with the aid of the micrometer inclusions;the growth ofγgrains can also be selectively restrained by the pinning effect of the nano-meter precipitates.After welding with a high-heat input of 400 kJ/cm,excellent HAZ toughness can be obtained in the steel plates with both of the above microstructures,and the average absorbed energy is greater than 200 J for the V-notch Charpy impact test at-20℃.展开更多
Conventional mechanical machining of a composite material comprising an aluminum matrix reinforced with a high volume fraction of SiC particles(hereinafter referred to as an SiCp/Al composite)faces problems such as ra...Conventional mechanical machining of a composite material comprising an aluminum matrix reinforced with a high volume fraction of SiC particles(hereinafter referred to as an SiCp/Al composite)faces problems such as rapid tool wear,high specific cutting force,and poor surface integrity.Instead,a promising method for solving these problems is laser-induced oxidation-assisted milling(LOAM):under laser irradiation,the local workpiece material reacts with oxygen,thus forming loose and porous oxides that are easily removed.In the present work,the oxidation mechanism of SiCp/Al irradiated by a nanosecond pulsed laser is studied to better understand the laser-induced oxidation behavior and control the characteristics of the oxides,with laser irradiation experiments performed on a 65%SiCp/Al composite with various laser parameters and auxiliary gases(oxygen,nitrogen,and argon).With increasing laser pulse energy density,both the ablated groove depth and the width of the heat-affected zone increase.When oxygen is used as the auxiliary gas,an oxide layer composed of SiO_(2)and Al2O3 forms,and CO_(2)is produced and escapes from the material,thereby forming pores in the oxides.However,when nitrogen or argon is used as the auxiliary gas,a recast layer is produced that is relatively difficult to remove.Under laser irradiation,the sputtered material reacts with oxygen to form oxides on both sides of the ablated groove,and as the laser scanning path advances,the produced oxides accumulate to form an oxide layer.LOAM and conventional milling are compared using the same milling parameters,and LOAM is found to be better for reduced milling force and tool wear and improved machined surface quality.展开更多
Studies of seven typical soil profiles showed that in the argillic soils derived from loess in the warmtemperate zone of China all the oxides of Fe, Mn, Al and Si were enriched with the accumulation of clayfraction in...Studies of seven typical soil profiles showed that in the argillic soils derived from loess in the warmtemperate zone of China all the oxides of Fe, Mn, Al and Si were enriched with the accumulation of clayfraction in the profiles. But owing to the influence of oxidation-reduction process the migration velocity ofFe and Mn was faster than that of clay. The free degrees of those metals were in the sequence Mn>Fe>Al,which reflected their different chemical activities in soil. In soils at the same level of development, the freedegree of iron and its activity, the free degree of Al, Alo/Alt× 100, SiO_2/R_2O_3, Sio/Sit× 100, and themagnetic susceptibility were relatively close to each other respectively. It might be considered that both thefres degrees of Fe and Al and Alo/Alt× 100 could serve as the distinctive indexes for argillic soils in warmtemperate zone. The paleoclimate corresponding to the fifth layer of paleosol (s_5) in Lnochuan, Shaanxiwas warmer and more humid than the present, and the paleoecological landscape approximated to today'sbioclimatic belt between the temperate deciduous broadleaved forest and the semiarid forest types.The Mossbouer spectra of the colloidal fraction (<1um) in the clayified horizon of argillic dark loessialsoil, cinnamon soil, brown earth and (s_5) paleosol indicated the superparamagnetic state at room temperature.The magnetic splitting six line spectra were observed clearly at 80 K. The results fitted with a computershowed that hematite and goethite were predominant in iron oxides and commonly existed as fine particles.The proportion of hematite and goethite in soil colloids varied considerably with different climates. Thehigher the temperature, the larger the proportion of hematite.展开更多
Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate m...Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate minerals with subordinate Cu-Pb arsenate minerals and minor Fe-Pb-Ba varieties. Based on their paragenesis these minerals may be divided into the following series: (1) the clinoclasite-olivenite-cornwallite- cornubite- debaoite- copper silicarsenate association, (2) the scorodite- carminite- beudan-tite-bayldonite- duftite association, and (3) the scorodite-Ba-bearing pharmacosiderite- dussertite association. Arsenate minerals are formed generally in the oxidized zone of the sulfide-type deposits which lie in thewarm, humid and rainy torrid-subtropical zone with pH=6-8 and contain large amounts of arsenopyrite andcarbonate rocks.展开更多
Graphene Oxide(GO),nanoscale Zero-Valent Iron(nZVI)and GO-modified nZVI(GO-nZVI)composite materials were prepared by the Hummer and polyphenol reduction method,respectively,and Scanning Electron Microscope(SEM)and X-r...Graphene Oxide(GO),nanoscale Zero-Valent Iron(nZVI)and GO-modified nZVI(GO-nZVI)composite materials were prepared by the Hummer and polyphenol reduction method,respectively,and Scanning Electron Microscope(SEM)and X-ray Diffraction(XRD)were used to characterize the morphology and phase composition of these materials.A series of batch experiments were then conducted to inves-tigate the performance and influencing factors of GO-nZVI activating peroxydisulfate(SPS)for the degra-dation of 1,2,3-trichloropropane(TCP).Finally,an in-situ oxidation reaction zone was created by GO-nZVI-activated SPS in a one-dimensional simulated system to study the remediation of TCP contamination under different aquifer conditions.The results showed that the GO-nZVI composite exhibited a porous,fluffy structure,with spherical nZVI particles loaded onto the surface and folds of the GO sheets.Compared with unmodified nZVI particles,the GO-nZVI composite significantly enhanced the removal efficiency of TCP by activated SPS,achieving a removal rate of 67.2%within an hour-78.2%higher than that of the unmodi-fied system.The SPS dosage and the C/Fe ratio in GO-nZVI were found to significantly affect the degradation efficiency of TCP.The removal rate of TCP increased with higher SPS concentration,and a 10%carbon addition,yielded the best activation effect.The one-dimensional simulation results indicated that the removal rate of TCP ranged from 30.1%to 73.3%under different conditions.A larger medium particle size and higher concentrations of reactants(SPS and GO-nZVI)improved pollutant degradation efficiency,increasing TCP removal by 62.1%,23.8%,and 3.7%,respectively.In contrast,a higher groundwater flow velocity was not conducive to the removal of pollutants,with the TCP removal rate decreasing by approxi-mately 41.9%.展开更多
To develop a melting-based larger-scale fabrication process for oxide dispersion strengthened(ODS)steel,this study proposed a method of zone melting with built-in precursor powder(ZMPP),followed by hot forging and agi...To develop a melting-based larger-scale fabrication process for oxide dispersion strengthened(ODS)steel,this study proposed a method of zone melting with built-in precursor powder(ZMPP),followed by hot forging and aging treatments.A 50 kg ingot was successfully prepared,highlighting the scalability of this innovative process.Microstructural analysis revealed a predominantly lath martensite matrix with a small amount of ferrite in the hot-forged ODS steel,without oxide particle aggregation.Aging at 750℃ resulted in the formation of sub-micron-sized Cr_(23)C_(6) particles at grain boundaries and martensitic lath interfaces,accompanied by a high-density(7.64×1023 m^(-3))nano-scale(~6 nm)Y-Si-O complex oxides after 25 h.Additionally,the hot-forged sample exhibited a high yield strength(871 MPa)but limited ductility(5.0%).Aging treatments led to an increase in ductility but a decrease in yield strength.Notably,prolonged aging maintained the strength level of steels while enhancing ductility,with a 23.3% total elongation observed after 25 h.The novel ZMPP method,preparing high-quality ODS steels with uniform microstructure and good mechanical properties,provided a new avenue for large-scale production of ODS steels.展开更多
文摘According to the oxidation intensity of ore-hosting sandstone, the interlayer oxidation zone of the Shihongtan sandstone-type uranium deposit in the Turpan-Hami basin can be divided into 4 geochemical subzones, namely, intenselyoxidized, weakly-oxidized, redox and unoxidized primary subzones. The elemental geochemical characteristics of the four subzones have been studied in detail, and the results show that U, together with other elements such as Re, Mo, Se, Sr, S, REE, Corganic etc., is enriched in the redox subzone. Re and U have similar geochemical properties in the reductionoxidation process. The geochemical properties of Mo and Se are similar to those of U in the reduction condition, but different from those of U in the oxidation condition. It is proposed that the ore-hosting layers can provide a curtain mount of uranium for uranium mineralization.
文摘Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.
基金support from the National Natural Science Foundation of China (No. U1960202)the Opening Foundation from Shanghai Engineering Research Center of Hot Manufacturing, China (No. 18DZ2253400)。
文摘This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.
基金supported by the National Key R&D Program of China(No.2022YFF0609300)the National Major Science and Technology Projects of China(J2019-VI-0021-0137).
文摘In the creep fatigue crack growth of GH4169 alloy,oxidation is a prominent damage source,which is mainly manifested as the oxidation damage zone in front of crack tip.In order to investigate the property of the oxidation damage zone formed in the creep fatigue crack growth,crack growth tests of directly aged GH4169 alloy were conducted at 650℃ in air under various load conditions.Interrupted tests were performed to observe the damage characteristics at crack tip.Block tests were systematically executed to quantify the dependency of oxidation damage zone size on load and holding time.The crack propagation of the GH4169 alloy has a close relationship with grain boundary oxidation at 650℃.An oxidation damage zone in front of crack tip includes intergranular microcracks and oxidised but uncracked grain boundaries.Its size has been calculated from transient crack growth rate and described as a function of maximum stress intensity factor and holding time.Based on oxidation damage zone size,a novel model has been developed to predict the creep fatigue crack growth rate of the GH4169 alloy at 650℃.
文摘The Sain Us gold deposit is a typical auriferous sulphide quartz vein deposit in the InnerMongolian arid steppe climatic region. The oxidation zone has been controlled by the arid cli-mate since the beginning of the Holocene. Gold supergene evolution is characterized by enlarge-ment of gold grains, complication of the gold form, raising of the gold grade and increase of thegold fineness; besides, gold and silver have two enrichment peaks at the same depth, which is insharp contrast to the unimodal enrichment of gold and silver and the occurrence of gold aboveand silver below in a humid climatic region. Sun pumping is the main cause for the bimodalenrichment of gold and silver. Illite 2 M_1 is one of the main causes for the upper enrichment peakof gold and silver.
基金NationalNaturalScienceFoundationofChina! (No .5 99740 2 0 )
文摘On the basis of heat transfer and chemical kinetics theory, both connections coal self ignite with oxygen concentration and range of oxidation zone with air leak intensity are analyzed, and calculating method is deduced to gain the lower limit of oxygen concentration and the range of oxidation zone. The change rule of correlative parameter is quantitatively researched between before nitrogen injection and after nitrogen injection in gob, such as oxygen concentration, oxidation zone width, etc. According to theoretical calculation, the relation position and flow of nitrogen injection with oxidation zone width is conformed, and computational formulas of the best flow and position of nitrogen injection are obtained. It offers a theoretic criterion for preventing and controlling float coal self ignite by nitrogen injection in gob.
基金Project(2011CB605503)supported by the National Basic Research Program of China
文摘The oxidation behavior of Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys at 800 °C for exposure time up to 100 h was examined. It is shown that oxidation rate of experimental alloys obeys the parabolic kinetics. Ti?22Al?26Nb?1Zr alloy demonstrates more excellent oxidation resistance than the other two alloys. The main oxidation products are TiO2, Al2O3 and AlNbO4 phases for all these alloys. For the Ti?22Al?26Nb?1Zr alloy, Zr addition can modify the growth mechanism of oxide scale, which can effectively hinder the diffusion of oxygen. Whereas, reaction of Zr with oxygen leads to the formation of ZrO2 precipitates for the Ti?22Al?21Nb?6Zr alloy, which promotes the oxygen ingress into the substrate. Meanwhile, oxidation affected zones, including internal-oxidation layer and oxygen-enriched zone, are present beneath the outmost oxide scale. The difference in these zones is derived from the phase constitution in the starting Ti?22Al?(27?x)Nb?xZr (x=0, 1, 6) alloys.
基金supported by the National Natural Science Foundation of China (No. 20877086 21077119)+5 种基金the National Basic Research Program (973) of China (No. 2009CB421103)the National Water Project of China (No. 2009ZX07209-005 2008ZX07421-001 2008ZX07209-006-02)the support of Beijing Nova Program (No. 2011104)K. C. Wong Education Foundation, Hong Kong
文摘The spatial distribution and diversity of archaeal and bacterial ammonia oxidizers （AOA and AOB） were evaluated targeting amoA genes in the gradient of a littoral buffer zone which has been identified as a hot spot for N cycling. Here we found high spatial heterogeneity in the nitrification rate and abundance of ammonia oxidizers in the five sampling sites. The bacterial amoA gene was numerically dominant in most of the surface soil but decreased dramatically in deep layers. Higher nitrification potentials were detected in two sites near the land/water interface at 4.4–6.1 μg NO2-N/（g dry weight soil·hr）, while only 1.0–1.7 μg NO2-N/（g dry weight soil·hr） was measured at other sites. The potential nitrification rates were proportional to the amoA gene abundance for AOB, but with no significant correlation with AOA. The NH4＋ concentration was the most determinative parameter for the abundance of AOB and potential nitrification rates in this study. Higher richness in the surface layer was found in the analysis of biodiversity. Phylogenetic analysis revealed that most of the bacterial amoA sequences in surface soil were affiliated with the genus of Nitrosopira while the archaeal sequences were almost equally affiliated with Candidatus ‘Nitrososphaera gargensis’ and Candidatus ‘Nitrosocaldus yellowstonii’. The spatial distribution of AOA and AOB indicated that bacteria may play a more important role in nitrification in the littoral buffer zone of a N-rich lake.
文摘Excellent Heat Affected Zone Toughness Technology Improved by use of Strong Deoxidizers(ETISD Technology)has been developed by Baosteel.When deoxidation of molten steel is conducted at the precisely controlled oxygen concentrations,the formation of the micro-meter inclusions and the nano-meter precipitates in the steel plate can be effectively controlled.During the welding process with high-heat input,the formation of acicular ferrite can be selectively promoted with the aid of micro-meter inclusions;the growth ofγgrain can also be selectively restrained by the pinning effect of nano-meter precipitates.After welding with high-heat input of 400 kJ/cm,excellent heat affected zone toughness can be obtained for the steel plates with both of the above microstructures,and the average absorbed energy is greater than 200 J for V notch Charpy impact test at-20℃.
基金the Key-Area Research and Development Program of Guangdong Province(2019B010936001)financially supported by the National Natural Science Foundation of China(Grant Nos.51671202 and 51301184)。
文摘A low-diffusion Ni Re Pt Al coating((Ni,Pt)Al outer layer in addition to a Re-rich diffusion barrier layer)was prepared on a Ni_(3)Al-base single crystal(SC)superalloy via electroplating and gaseous aluminizing treatments,wherein the electroplating procedures consisted of the composite deposition of Ni-Re followed by electroplating of Pt.In order to perform a comparison with conventional Ni Al and(Ni,Pt)Al coatings,the cyclic oxidation performance of the Ni Re Pt Al coating was evaluated at 1100 and 1150℃.We observed that the oxidation resistance of the Ni Re Pt Al coating was significantly improved by the greater presence of the residualβ-Ni Al phase in the outer layer and the lesser outward-diffusion of Mo from the substrate.In addition,the coating with the Re-rich diffusion barrier demonstrated a lower extent of interdiffusion into the substrate,where the thickness of the second reaction zone(SRZ)in the substrate alloy decreased by 25%.The mechanisms responsible for improving the oxidation resistance and decreasing the extent of SRZ formation are discussed,in which a particular attention is paid to the inhibition of the outward diffusion of Mo by the Re-based diffusion barrier.
文摘Excellent heat affected zone(HAZ)toughness technology improved by strong deoxidizers(ETISI)technology has been developed by Baosteel.In the deoxidation process of molten steel by adding strong deoxidizers,the formation of micrometer inclusions and nano-meter precipitates in steel plates can be effectively controlled by a precise control of oxygen concentration.In the welding process with a high-heat input,the formation of acicular ferrite can be selectively promoted with the aid of the micrometer inclusions;the growth ofγgrains can also be selectively restrained by the pinning effect of the nano-meter precipitates.After welding with a high-heat input of 400 kJ/cm,excellent HAZ toughness can be obtained in the steel plates with both of the above microstructures,and the average absorbed energy is greater than 200 J for the V-notch Charpy impact test at-20℃.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.NT2021020)。
文摘Conventional mechanical machining of a composite material comprising an aluminum matrix reinforced with a high volume fraction of SiC particles(hereinafter referred to as an SiCp/Al composite)faces problems such as rapid tool wear,high specific cutting force,and poor surface integrity.Instead,a promising method for solving these problems is laser-induced oxidation-assisted milling(LOAM):under laser irradiation,the local workpiece material reacts with oxygen,thus forming loose and porous oxides that are easily removed.In the present work,the oxidation mechanism of SiCp/Al irradiated by a nanosecond pulsed laser is studied to better understand the laser-induced oxidation behavior and control the characteristics of the oxides,with laser irradiation experiments performed on a 65%SiCp/Al composite with various laser parameters and auxiliary gases(oxygen,nitrogen,and argon).With increasing laser pulse energy density,both the ablated groove depth and the width of the heat-affected zone increase.When oxygen is used as the auxiliary gas,an oxide layer composed of SiO_(2)and Al2O3 forms,and CO_(2)is produced and escapes from the material,thereby forming pores in the oxides.However,when nitrogen or argon is used as the auxiliary gas,a recast layer is produced that is relatively difficult to remove.Under laser irradiation,the sputtered material reacts with oxygen to form oxides on both sides of the ablated groove,and as the laser scanning path advances,the produced oxides accumulate to form an oxide layer.LOAM and conventional milling are compared using the same milling parameters,and LOAM is found to be better for reduced milling force and tool wear and improved machined surface quality.
文摘Studies of seven typical soil profiles showed that in the argillic soils derived from loess in the warmtemperate zone of China all the oxides of Fe, Mn, Al and Si were enriched with the accumulation of clayfraction in the profiles. But owing to the influence of oxidation-reduction process the migration velocity ofFe and Mn was faster than that of clay. The free degrees of those metals were in the sequence Mn>Fe>Al,which reflected their different chemical activities in soil. In soils at the same level of development, the freedegree of iron and its activity, the free degree of Al, Alo/Alt× 100, SiO_2/R_2O_3, Sio/Sit× 100, and themagnetic susceptibility were relatively close to each other respectively. It might be considered that both thefres degrees of Fe and Al and Alo/Alt× 100 could serve as the distinctive indexes for argillic soils in warmtemperate zone. The paleoclimate corresponding to the fifth layer of paleosol (s_5) in Lnochuan, Shaanxiwas warmer and more humid than the present, and the paleoecological landscape approximated to today'sbioclimatic belt between the temperate deciduous broadleaved forest and the semiarid forest types.The Mossbouer spectra of the colloidal fraction (<1um) in the clayified horizon of argillic dark loessialsoil, cinnamon soil, brown earth and (s_5) paleosol indicated the superparamagnetic state at room temperature.The magnetic splitting six line spectra were observed clearly at 80 K. The results fitted with a computershowed that hematite and goethite were predominant in iron oxides and commonly existed as fine particles.The proportion of hematite and goethite in soil colloids varied considerably with different climates. Thehigher the temperature, the larger the proportion of hematite.
文摘Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate minerals with subordinate Cu-Pb arsenate minerals and minor Fe-Pb-Ba varieties. Based on their paragenesis these minerals may be divided into the following series: (1) the clinoclasite-olivenite-cornwallite- cornubite- debaoite- copper silicarsenate association, (2) the scorodite- carminite- beudan-tite-bayldonite- duftite association, and (3) the scorodite-Ba-bearing pharmacosiderite- dussertite association. Arsenate minerals are formed generally in the oxidized zone of the sulfide-type deposits which lie in thewarm, humid and rainy torrid-subtropical zone with pH=6-8 and contain large amounts of arsenopyrite andcarbonate rocks.
基金financially supported by the Basal Research Fund of Chinese Academy of Geological Sciences(NO.SK202318)the Natural Science Foundation of Xiamen,China(No.3502Z20227309)the Natural Science Foundation of Fujian Province of China(NO.2023J01227).
文摘Graphene Oxide(GO),nanoscale Zero-Valent Iron(nZVI)and GO-modified nZVI(GO-nZVI)composite materials were prepared by the Hummer and polyphenol reduction method,respectively,and Scanning Electron Microscope(SEM)and X-ray Diffraction(XRD)were used to characterize the morphology and phase composition of these materials.A series of batch experiments were then conducted to inves-tigate the performance and influencing factors of GO-nZVI activating peroxydisulfate(SPS)for the degra-dation of 1,2,3-trichloropropane(TCP).Finally,an in-situ oxidation reaction zone was created by GO-nZVI-activated SPS in a one-dimensional simulated system to study the remediation of TCP contamination under different aquifer conditions.The results showed that the GO-nZVI composite exhibited a porous,fluffy structure,with spherical nZVI particles loaded onto the surface and folds of the GO sheets.Compared with unmodified nZVI particles,the GO-nZVI composite significantly enhanced the removal efficiency of TCP by activated SPS,achieving a removal rate of 67.2%within an hour-78.2%higher than that of the unmodi-fied system.The SPS dosage and the C/Fe ratio in GO-nZVI were found to significantly affect the degradation efficiency of TCP.The removal rate of TCP increased with higher SPS concentration,and a 10%carbon addition,yielded the best activation effect.The one-dimensional simulation results indicated that the removal rate of TCP ranged from 30.1%to 73.3%under different conditions.A larger medium particle size and higher concentrations of reactants(SPS and GO-nZVI)improved pollutant degradation efficiency,increasing TCP removal by 62.1%,23.8%,and 3.7%,respectively.In contrast,a higher groundwater flow velocity was not conducive to the removal of pollutants,with the TCP removal rate decreasing by approxi-mately 41.9%.
基金financially supported by the National Natural Science Foundation of China(Nos.52271034,52301058 and 52471042)the National MCF Energy R&D Program of China(No.2018YFE0306102)+1 种基金the China Postdoctoral Science Foundation(No.2023M732183)the Postdoctoral Fellowship Program of CPSF(No.GZB20230399).
文摘To develop a melting-based larger-scale fabrication process for oxide dispersion strengthened(ODS)steel,this study proposed a method of zone melting with built-in precursor powder(ZMPP),followed by hot forging and aging treatments.A 50 kg ingot was successfully prepared,highlighting the scalability of this innovative process.Microstructural analysis revealed a predominantly lath martensite matrix with a small amount of ferrite in the hot-forged ODS steel,without oxide particle aggregation.Aging at 750℃ resulted in the formation of sub-micron-sized Cr_(23)C_(6) particles at grain boundaries and martensitic lath interfaces,accompanied by a high-density(7.64×1023 m^(-3))nano-scale(~6 nm)Y-Si-O complex oxides after 25 h.Additionally,the hot-forged sample exhibited a high yield strength(871 MPa)but limited ductility(5.0%).Aging treatments led to an increase in ductility but a decrease in yield strength.Notably,prolonged aging maintained the strength level of steels while enhancing ductility,with a 23.3% total elongation observed after 25 h.The novel ZMPP method,preparing high-quality ODS steels with uniform microstructure and good mechanical properties,provided a new avenue for large-scale production of ODS steels.
