A simpler and more convenient method for producing wear-resistant, TiC-reinforced coatings were investigated in this study. It consists of the simultaneous synthesis and deposition of TiC-Fe materials by oxyacetylene ...A simpler and more convenient method for producing wear-resistant, TiC-reinforced coatings were investigated in this study. It consists of the simultaneous synthesis and deposition of TiC-Fe materials by oxyacetylene flame spraying. Solid reagents bound together to form a single particle are injected into the flame stream where an in-situ reaction occurs. The reaction products are propelled onto a substrate to form a coating. Microstructural analyses reveal that TiC and Fe are the dominant phases in the coatings. The reaction between Ti and C happens step by step along with the reactive spray powder flight, and TiC-Fe materials were mainly synthesized where the spray distance is 125-170 mm. The TiC-Fe coatings are composed of alternate TiC-rich and TiC-poor lamellae with different microhardness of 11.9-13.7 and 3.0-6.0 GPa, respectively. Submicron and round TiC particles are dispersed within a ductile metal matrix. The peculiar microstructure is thought to be responsible for its good wear resistance, which is better nearly five times than WC-reinforced cermet coatings obtained by traditional oxyacetylene flame spray.展开更多
By means of an inherent elevated-temperature of poured liquid steel,a Ti-C-30wt%Fe preform,which was pre-placed in a mould cavity,was directly ignited and a combustion synthesis reaction took place.As a result,a TiC-F...By means of an inherent elevated-temperature of poured liquid steel,a Ti-C-30wt%Fe preform,which was pre-placed in a mould cavity,was directly ignited and a combustion synthesis reaction took place.As a result,a TiC-Fe cermet coating with a thickness of about 10mm was simultaneously synthesized on the solidified steel matrix.The synthesized coating exhibits a feature of graded composite structure,in which both the amount and size of TiC particles decrease gradually with an increasing distance from the furface of the coating.Moreover,by a proper casting technique,the pores formed during the combustion synthesis of the preform could be centrally distributed in 2-3mm in outer layer of the coating.When this outer porous layer was worn off,the rest coating with a thickness of about 8mm possesses a dense structure and a high abrasive wear resistance.展开更多
A new hardfacing process, reactive braze coating process (RBCC) was studied, and (TiC+Cr_3C_2)/Fe composite coatings were prepared by RBCC using carbon, Cr_3C_2, iron, ferrochromium and titanium powder as the raw mate...A new hardfacing process, reactive braze coating process (RBCC) was studied, and (TiC+Cr_3C_2)/Fe composite coatings were prepared by RBCC using carbon, Cr_3C_2, iron, ferrochromium and titanium powder as the raw materials in vacuum braze furnace. The results show that TiC is in-situ synthesized in the coatings. The methods of introducing Cr_3C_2 have great effects on the distribution of TiC. Adding Cr_3C_2 directly to the raw materials for coatings, fine TiC particles aggregate into discoids parallel to the coating surface, whereas, in-situ synthesizing Cr_3C_2 in coatings, the aggregations of TiC are lumpish. During braze coating, Cr_3C_2 particles directly added dissolve and precipitate to become needle-shaped. The coatings have an even and smooth surface and are combined with their mild steel substrates by a metallurgical bonding.展开更多
The Fe-based alloy coatings reinforced with in situ synthesized TiB2-TiC were prepared on Q235 steel by reactive plasma cladding using Fe901 alloy, Ti, B4C, and graphite （C） powders us raw materials. The effects of ...The Fe-based alloy coatings reinforced with in situ synthesized TiB2-TiC were prepared on Q235 steel by reactive plasma cladding using Fe901 alloy, Ti, B4C, and graphite （C） powders us raw materials. The effects of C/B4C weight percentage ratio （0 - 1. 38 ） on the microstructure , microhardness , and wet sand abrasion resistance of the coatings were investigated. The results show that the coatings consist of （ Fe, Cr ） solid solution, TiC, TiB2, Ti8C5 , and Fe3 C phases. The decrease of C/B4 C ratio is propitious to the formation of TiB2 and Tis C5. Increasing the C/B4 C ratio can help to refine the microstructure of the coatings. However, the microhardness of the middle-upper of the coatings and the wet sand abrasion resistance of the coatings degenerate with the increase of C/B4C ratio. The coating exhibits the best wet sand abrasion resistance at C/BaC =0 and its average mass loss rate per unit wear distance is 0. 001 2%/m. The change of the wet sand abrasion resistance of the coatings with the C/B4C ratio can be mainly attributed to the combined action of the changes of microhardness and the volume percentage of the ceramic reinforcements containing titanium in the coatings.展开更多
Mierostrueture of the Fe-based alloy hardfaeing coating reinforced by TiC-VC particles was investigated by means of SEM, TEM, XRD and EPMA. The thermodynamics and effect of elements on the carbides were discussed. The...Mierostrueture of the Fe-based alloy hardfaeing coating reinforced by TiC-VC particles was investigated by means of SEM, TEM, XRD and EPMA. The thermodynamics and effect of elements on the carbides were discussed. The result shows that TiC-VC carbides can be formed during arc welding. Carbides with particle size of 2 ～4μm are uniformly dispersed in the matrix. Evidently the covering components and their amount affect the microstrueture and hardness of the coatings. An excellent microstructure and hardness of hardfacing coating were obtained, while the amount of graphite, FeTi and FeV was controlled within the range of 8%- 10%, 15%- 18% and 8%- 12%, respectively.展开更多
The dense TiC Fe cermets were produced by self propagating high temperature synthesis and pseudo hot isostatic pressing(SHS/PHIP). The influence of Fe content on the combustion temperature, combustion velocity, densit...The dense TiC Fe cermets were produced by self propagating high temperature synthesis and pseudo hot isostatic pressing(SHS/PHIP). The influence of Fe content on the combustion temperature, combustion velocity, density and microstructure of products was studied. The composition and microstructure of the product were analyzed. The results showed that the cermet consists of quasi spherical TiC particles and Fe binder phases. A thin diffusion layer was found between Fe binder phase and TiC particle. In the range of 10%～20% Fe content, the combustion temperature and velocity decrease more slowly than the other contributions.展开更多
以TiFe粉和碳的前驱体(石油沥青)为原料,通过碳化制备Ti Fe C系反应喷涂复合粉末,并通过普通火焰喷涂技术成功制备了TiC/Fe金属陶瓷复合涂层;采用XRD、SEM和EDS对喷涂粉末和涂层的成分、组织结构进行了分析,同时对涂层耐磨性能进行了对...以TiFe粉和碳的前驱体(石油沥青)为原料,通过碳化制备Ti Fe C系反应喷涂复合粉末,并通过普通火焰喷涂技术成功制备了TiC/Fe金属陶瓷复合涂层;采用XRD、SEM和EDS对喷涂粉末和涂层的成分、组织结构进行了分析,同时对涂层耐磨性能进行了对比研究。结果表明:采用前驱体碳化复合技术制备的Ti Fe C系复合喷涂粉末粒度均匀、无有害相生成;喷涂所得到的TiC/Fe金属陶瓷复合涂层由片状的铁基体和弥散分布的TiC颗粒组成;TiC颗粒大致呈球形,粒度一般在0.5μm以下;相同条件下所获涂层的磨损体积大约是常规火焰喷涂Ni60涂层的1/5。展开更多
基金This work was supported by the National "863" Project of China under grant No. 715-009-0130.
文摘A simpler and more convenient method for producing wear-resistant, TiC-reinforced coatings were investigated in this study. It consists of the simultaneous synthesis and deposition of TiC-Fe materials by oxyacetylene flame spraying. Solid reagents bound together to form a single particle are injected into the flame stream where an in-situ reaction occurs. The reaction products are propelled onto a substrate to form a coating. Microstructural analyses reveal that TiC and Fe are the dominant phases in the coatings. The reaction between Ti and C happens step by step along with the reactive spray powder flight, and TiC-Fe materials were mainly synthesized where the spray distance is 125-170 mm. The TiC-Fe coatings are composed of alternate TiC-rich and TiC-poor lamellae with different microhardness of 11.9-13.7 and 3.0-6.0 GPa, respectively. Submicron and round TiC particles are dispersed within a ductile metal matrix. The peculiar microstructure is thought to be responsible for its good wear resistance, which is better nearly five times than WC-reinforced cermet coatings obtained by traditional oxyacetylene flame spray.
基金FinanciallysupportedbytheNationalNaturalScienceFoundationofChina (No .5 0 2 76 0 2 3)
文摘By means of an inherent elevated-temperature of poured liquid steel,a Ti-C-30wt%Fe preform,which was pre-placed in a mould cavity,was directly ignited and a combustion synthesis reaction took place.As a result,a TiC-Fe cermet coating with a thickness of about 10mm was simultaneously synthesized on the solidified steel matrix.The synthesized coating exhibits a feature of graded composite structure,in which both the amount and size of TiC particles decrease gradually with an increasing distance from the furface of the coating.Moreover,by a proper casting technique,the pores formed during the combustion synthesis of the preform could be centrally distributed in 2-3mm in outer layer of the coating.When this outer porous layer was worn off,the rest coating with a thickness of about 8mm possesses a dense structure and a high abrasive wear resistance.
文摘A new hardfacing process, reactive braze coating process (RBCC) was studied, and (TiC+Cr_3C_2)/Fe composite coatings were prepared by RBCC using carbon, Cr_3C_2, iron, ferrochromium and titanium powder as the raw materials in vacuum braze furnace. The results show that TiC is in-situ synthesized in the coatings. The methods of introducing Cr_3C_2 have great effects on the distribution of TiC. Adding Cr_3C_2 directly to the raw materials for coatings, fine TiC particles aggregate into discoids parallel to the coating surface, whereas, in-situ synthesizing Cr_3C_2 in coatings, the aggregations of TiC are lumpish. During braze coating, Cr_3C_2 particles directly added dissolve and precipitate to become needle-shaped. The coatings have an even and smooth surface and are combined with their mild steel substrates by a metallurgical bonding.
基金This work is supported by the National Natural Science Foundation of China （Grant No. 51101051 ）, the Natural Science Foundation of Jiangsu Province （Grant No. BK2011250）, and Jiangsu Planned Projects for Postdoctoral Research Funds （Grant No. 1101017 C）.
文摘The Fe-based alloy coatings reinforced with in situ synthesized TiB2-TiC were prepared on Q235 steel by reactive plasma cladding using Fe901 alloy, Ti, B4C, and graphite （C） powders us raw materials. The effects of C/B4C weight percentage ratio （0 - 1. 38 ） on the microstructure , microhardness , and wet sand abrasion resistance of the coatings were investigated. The results show that the coatings consist of （ Fe, Cr ） solid solution, TiC, TiB2, Ti8C5 , and Fe3 C phases. The decrease of C/B4 C ratio is propitious to the formation of TiB2 and Tis C5. Increasing the C/B4 C ratio can help to refine the microstructure of the coatings. However, the microhardness of the middle-upper of the coatings and the wet sand abrasion resistance of the coatings degenerate with the increase of C/B4C ratio. The coating exhibits the best wet sand abrasion resistance at C/BaC =0 and its average mass loss rate per unit wear distance is 0. 001 2%/m. The change of the wet sand abrasion resistance of the coatings with the C/B4C ratio can be mainly attributed to the combined action of the changes of microhardness and the volume percentage of the ceramic reinforcements containing titanium in the coatings.
文摘Mierostrueture of the Fe-based alloy hardfaeing coating reinforced by TiC-VC particles was investigated by means of SEM, TEM, XRD and EPMA. The thermodynamics and effect of elements on the carbides were discussed. The result shows that TiC-VC carbides can be formed during arc welding. Carbides with particle size of 2 ～4μm are uniformly dispersed in the matrix. Evidently the covering components and their amount affect the microstrueture and hardness of the coatings. An excellent microstructure and hardness of hardfacing coating were obtained, while the amount of graphite, FeTi and FeV was controlled within the range of 8%- 10%, 15%- 18% and 8%- 12%, respectively.
文摘The dense TiC Fe cermets were produced by self propagating high temperature synthesis and pseudo hot isostatic pressing(SHS/PHIP). The influence of Fe content on the combustion temperature, combustion velocity, density and microstructure of products was studied. The composition and microstructure of the product were analyzed. The results showed that the cermet consists of quasi spherical TiC particles and Fe binder phases. A thin diffusion layer was found between Fe binder phase and TiC particle. In the range of 10%～20% Fe content, the combustion temperature and velocity decrease more slowly than the other contributions.
文摘以TiFe粉和碳的前驱体(石油沥青)为原料,通过碳化制备Ti Fe C系反应喷涂复合粉末,并通过普通火焰喷涂技术成功制备了TiC/Fe金属陶瓷复合涂层;采用XRD、SEM和EDS对喷涂粉末和涂层的成分、组织结构进行了分析,同时对涂层耐磨性能进行了对比研究。结果表明:采用前驱体碳化复合技术制备的Ti Fe C系复合喷涂粉末粒度均匀、无有害相生成;喷涂所得到的TiC/Fe金属陶瓷复合涂层由片状的铁基体和弥散分布的TiC颗粒组成;TiC颗粒大致呈球形,粒度一般在0.5μm以下;相同条件下所获涂层的磨损体积大约是常规火焰喷涂Ni60涂层的1/5。
