In order to solve the high-price and short-lifetime problems of the cutter of agricultural machinery,and improve the wear resistance of the cutter, the TiCN/Fe metal ceramic composite coating was prepared on the subst...In order to solve the high-price and short-lifetime problems of the cutter of agricultural machinery,and improve the wear resistance of the cutter, the TiCN/Fe metal ceramic composite coating was prepared on the substrate of Q235 steel by reaction nitrogen arc cladding technique. The mixture powder of titanium and graphite was preplaced on the Q235 steel surface after intensive mixing by planetary ball mill and gluing with starch binder. The microstructure and phase of the coatings, interface behavior between coatings and the substrate were investigated by scanning electronic microscope and X-ray diffractometer. The micro-hardness distribution of the coating section was tested by micro-hardness tester. Friction coefficient and wear weight loss were measured by abrasion machine. Wearing surface morphology was investigated by scanning electronic microscope. The results show that an excellent bonding between the coatings and the Q235 steel substrate is ensured by the strong metallurgical interface and phase of the coatings. The coatings are mainly composed of TiCN. The highest micro- hardness of the coatings reaches 1 089 HV0. 2, while the micro-hardness of Q235 steel substrate is only about 286 HV0. 2. The anti-abrasive test results show that the wear resistance of the cladding coating is better than that of quenched and tempered 65 Mn steel which is often used as cutter of agricultural machinery. The field test results show that the TiCN/ Fe metal ceramic composite coating prepared by reaction nitrogen arc cladding is feasible to the manufacture and remanufacture of the cutter of agricultural machinery.展开更多
An in-situ synthesized TiCN particle reinforce composite coating was fabricated on Q235 steel substrate by nitrogen arc cladding technique, wherein the titanium powder and the graphite powder as original material were...An in-situ synthesized TiCN particle reinforce composite coating was fabricated on Q235 steel substrate by nitrogen arc cladding technique, wherein the titanium powder and the graphite powder as original material were intensively mixed by ball-miU and glued with starch binder, then preplaced onto the Q235 steel substrate. The microstructures and interfacial behavior were investigated by scanning electron microscopy. The phase of the coatings was investigated by X-ray diffractometer. The microhardness was tested by microhardness tester. The anti-abrasive pe^Cormance was tested by abrasion machine. The results show that an excellent bonding between the coatings and carbon steel substrate is ensured by the strong metallurgical inteoCace and phases of the coatings are mainly composed of TiCN. The highest microhardness of the coatings reaches 810HV0. 5, which is about 3 times more than that of the Q235 substrate. The anti-abrasive test results indicate that the coating is more anti-abrasive than the Q235 substrate.展开更多
A prototype of Pulsed Plasma Arc Cladding system was developed, in which single power source supplies both transferred plasma arc (TPA) and non-transferred plasma arc (N-TPA). Both plasmas work in turn in a high frequ...A prototype of Pulsed Plasma Arc Cladding system was developed, in which single power source supplies both transferred plasma arc (TPA) and non-transferred plasma arc (N-TPA). Both plasmas work in turn in a high frequency controlled by an IGBT connecting nozzle and workpiece. The working frequency of IGBT ranges from 50 ～ 7 000 Hz, in which the plasmas can work in turn smoothly. Higher than 500 Hz of working frequency is suggested for promotion of cladding quality and protection of IGBT. Drag phenomenon of TPA intensifies as the frequency goes up, which tends to increase the current proportion of TPA and suppress N-TPA. The occupation ratio of IGBT can be regulated from 5% ～ 95%, which balances the power supplies of both plasmas. An occupation ratio higher than 50% gives adequate proportion of arc current for N-TPA to preheat powder.展开更多
A longitudinal magnetic field was introduced to submerged arc cladding （SAC）. Electromagnetic stirring was caused by the interaction between arc plasma and external magnetic field. The grain size was refined and the...A longitudinal magnetic field was introduced to submerged arc cladding （SAC）. Electromagnetic stirring was caused by the interaction between arc plasma and external magnetic field. The grain size was refined and the average hardness was improved. On the base of a group of optimized parameters calculated by orthogonal optimization, some tests were made to study the effects of electromagnetic stirring on hardness and grain size of surfacing layers. It was confirmed that the solidification made of liquid metal could be improved by electromagnetic stirring and hardness and grain size of surfacing layers could be improved.展开更多
A wear-resistant （Cr, Fe）7C3/γ-Fe in situ ceramal composite coating was fabricated on the substrate of 0.45wt%C carbon steel by a plasma-transferred arc cladding process using the Fe-Cr-C elemental powder blends. T...A wear-resistant （Cr, Fe）7C3/γ-Fe in situ ceramal composite coating was fabricated on the substrate of 0.45wt%C carbon steel by a plasma-transferred arc cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness, and dry-sliding wear resistance of the coating were evaluated. The results indicate that the microstructure of the coating, which was composed of （Cr, Fe）7C3 primary phase uniformly distributed in the γ-Fe, and the （Cr, Fe）7C3 eutectic matrix was metallurgically bonded to the 0.45wt%C carbon steel substrate. From substrate to coating, the microstructure of the coating exhibited an evident epitaxial growth character. The coating, indehiscent and tack-free, had high hardness and appropriate gradient. It had excellent wear resistance under the dry sliding wear test condition.展开更多
The effect of electromagnetic stirring on the microstructure and wear behavior of coatings has been investigated. A series of iron-based coatings were fabricated by the plasma-transferred arc cladding process by apply...The effect of electromagnetic stirring on the microstructure and wear behavior of coatings has been investigated. A series of iron-based coatings were fabricated by the plasma-transferred arc cladding process by applying different magnetic field currents. The microstructure and wear resistance of the composite coatings were characterized by scanning electron microscope （SEM）, en- ergy dispersive X-ray analysis （EDAX）, X-ray diffraction （XRD）, and wet sand rubber wheel abrasion tester. The experimental results showed that the microstructure of the coatings was mainly the γ-Fe matrix and （Cr, Fe）7C3 carbide reinforced phase. The coatings were metallurgically bonded to the substrate. With increasing magnetic field current, the amount of the block-like （Cr, Fe）TC3 carbide reinforced phase increased at first, reached a local maximum, and then decreased sharply. When the magnetic field current reached 3 A, the block-like （Cr, Fe）TC3 carbides with high volume fraction were uniformly distributed in the matrix and the coating displayed a high microhardness and an excellent wear resistance under the wear test condition.展开更多
A wear resistant （Cr, Fe）7C3/γ-Fe ceramalcomposite coating wasfabricatedon substrate of a 0.45% C carbon steel by plasma transferred arc （PTA） cladding process using the Fe-Cr-C elemental powder blends. The micro...A wear resistant （Cr, Fe）7C3/γ-Fe ceramalcomposite coating wasfabricatedon substrate of a 0.45% C carbon steel by plasma transferred arc （PTA） cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness and dry sliding wear resistance of the coating were evaluated. Results indicate that the plasma transferred arc clad ceramal composite coating has a rapidly solidified microstructure consisting of blocky primary （Cr, Fe）7C3 and the interblocky （ Cr, Fe）7C3/γ-Fe eutectics and is metallurgically bonded to the 0.45%C carbon steel substrate. The ceramal composite coating has high hardness and excellent wear resistance under dry sliding wear test condition.展开更多
基金financially supported by the Natural Science Foundation of Hebei Province for Distinguished Young Scientists(No.E2011204036)the Natural Science Foundation of Hebei Province(No.E2014204028)the Youth Fund of Hebei Education Department(No.QN2014100)
文摘In order to solve the high-price and short-lifetime problems of the cutter of agricultural machinery,and improve the wear resistance of the cutter, the TiCN/Fe metal ceramic composite coating was prepared on the substrate of Q235 steel by reaction nitrogen arc cladding technique. The mixture powder of titanium and graphite was preplaced on the Q235 steel surface after intensive mixing by planetary ball mill and gluing with starch binder. The microstructure and phase of the coatings, interface behavior between coatings and the substrate were investigated by scanning electronic microscope and X-ray diffractometer. The micro-hardness distribution of the coating section was tested by micro-hardness tester. Friction coefficient and wear weight loss were measured by abrasion machine. Wearing surface morphology was investigated by scanning electronic microscope. The results show that an excellent bonding between the coatings and the Q235 steel substrate is ensured by the strong metallurgical interface and phase of the coatings. The coatings are mainly composed of TiCN. The highest micro- hardness of the coatings reaches 1 089 HV0. 2, while the micro-hardness of Q235 steel substrate is only about 286 HV0. 2. The anti-abrasive test results show that the wear resistance of the cladding coating is better than that of quenched and tempered 65 Mn steel which is often used as cutter of agricultural machinery. The field test results show that the TiCN/ Fe metal ceramic composite coating prepared by reaction nitrogen arc cladding is feasible to the manufacture and remanufacture of the cutter of agricultural machinery.
基金This research was financially supported by Natural Science Foundation of Hebei Province for Distinguished Young Scientists （ No. E2011204036）.
文摘An in-situ synthesized TiCN particle reinforce composite coating was fabricated on Q235 steel substrate by nitrogen arc cladding technique, wherein the titanium powder and the graphite powder as original material were intensively mixed by ball-miU and glued with starch binder, then preplaced onto the Q235 steel substrate. The microstructures and interfacial behavior were investigated by scanning electron microscopy. The phase of the coatings was investigated by X-ray diffractometer. The microhardness was tested by microhardness tester. The anti-abrasive pe^Cormance was tested by abrasion machine. The results show that an excellent bonding between the coatings and carbon steel substrate is ensured by the strong metallurgical inteoCace and phases of the coatings are mainly composed of TiCN. The highest microhardness of the coatings reaches 810HV0. 5, which is about 3 times more than that of the Q235 substrate. The anti-abrasive test results indicate that the coating is more anti-abrasive than the Q235 substrate.
文摘A prototype of Pulsed Plasma Arc Cladding system was developed, in which single power source supplies both transferred plasma arc (TPA) and non-transferred plasma arc (N-TPA). Both plasmas work in turn in a high frequency controlled by an IGBT connecting nozzle and workpiece. The working frequency of IGBT ranges from 50 ～ 7 000 Hz, in which the plasmas can work in turn smoothly. Higher than 500 Hz of working frequency is suggested for promotion of cladding quality and protection of IGBT. Drag phenomenon of TPA intensifies as the frequency goes up, which tends to increase the current proportion of TPA and suppress N-TPA. The occupation ratio of IGBT can be regulated from 5% ～ 95%, which balances the power supplies of both plasmas. An occupation ratio higher than 50% gives adequate proportion of arc current for N-TPA to preheat powder.
文摘A longitudinal magnetic field was introduced to submerged arc cladding （SAC）. Electromagnetic stirring was caused by the interaction between arc plasma and external magnetic field. The grain size was refined and the average hardness was improved. On the base of a group of optimized parameters calculated by orthogonal optimization, some tests were made to study the effects of electromagnetic stirring on hardness and grain size of surfacing layers. It was confirmed that the solidification made of liquid metal could be improved by electromagnetic stirring and hardness and grain size of surfacing layers could be improved.
文摘A wear-resistant （Cr, Fe）7C3/γ-Fe in situ ceramal composite coating was fabricated on the substrate of 0.45wt%C carbon steel by a plasma-transferred arc cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness, and dry-sliding wear resistance of the coating were evaluated. The results indicate that the microstructure of the coating, which was composed of （Cr, Fe）7C3 primary phase uniformly distributed in the γ-Fe, and the （Cr, Fe）7C3 eutectic matrix was metallurgically bonded to the 0.45wt%C carbon steel substrate. From substrate to coating, the microstructure of the coating exhibited an evident epitaxial growth character. The coating, indehiscent and tack-free, had high hardness and appropriate gradient. It had excellent wear resistance under the dry sliding wear test condition.
基金This study was financially supported by the Major State Basic Research Development Program of China (973 Program, No.2007CB607601)the National Natural Science Foundation of China (No.50735006)
文摘The effect of electromagnetic stirring on the microstructure and wear behavior of coatings has been investigated. A series of iron-based coatings were fabricated by the plasma-transferred arc cladding process by applying different magnetic field currents. The microstructure and wear resistance of the composite coatings were characterized by scanning electron microscope （SEM）, en- ergy dispersive X-ray analysis （EDAX）, X-ray diffraction （XRD）, and wet sand rubber wheel abrasion tester. The experimental results showed that the microstructure of the coatings was mainly the γ-Fe matrix and （Cr, Fe）7C3 carbide reinforced phase. The coatings were metallurgically bonded to the substrate. With increasing magnetic field current, the amount of the block-like （Cr, Fe）TC3 carbide reinforced phase increased at first, reached a local maximum, and then decreased sharply. When the magnetic field current reached 3 A, the block-like （Cr, Fe）TC3 carbides with high volume fraction were uniformly distributed in the matrix and the coating displayed a high microhardness and an excellent wear resistance under the wear test condition.
文摘A wear resistant （Cr, Fe）7C3/γ-Fe ceramalcomposite coating wasfabricatedon substrate of a 0.45% C carbon steel by plasma transferred arc （PTA） cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness and dry sliding wear resistance of the coating were evaluated. Results indicate that the plasma transferred arc clad ceramal composite coating has a rapidly solidified microstructure consisting of blocky primary （Cr, Fe）7C3 and the interblocky （ Cr, Fe）7C3/γ-Fe eutectics and is metallurgically bonded to the 0.45%C carbon steel substrate. The ceramal composite coating has high hardness and excellent wear resistance under dry sliding wear test condition.
