Fe-Cr-Ti-C composite powder was synthesized by precursor carbonization-composition process using the mixture of ferrotitanium, chromium, iron powder and precursor sucrose as raw material. And then the Fe-Cr-Ti-C coati...Fe-Cr-Ti-C composite powder was synthesized by precursor carbonization-composition process using the mixture of ferrotitanium, chromium, iron powder and precursor sucrose as raw material. And then the Fe-Cr-Ti-C coating was prepared by reactive plasma cladding method. Microstructure of the samples was observed by scanning electron microscope （SEM）, the phases were determined by X-ray diffraction （XRD）, and the wear resistance was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the composite coating consists of primary austenite and dendritic eutectic austenite, chrysanthemum-shaped eutectic （Cr, Fe ） 7 C3 and TiC carbide. TiC presents the gradient distribution and different shapes in the coating, corresponding to equiaxial structure both in fusion zone and central zone, while it presents dendritic structure on the surface, respectively. The wear mass loss is insensitive to load for the coating while it increases rapidly for Q235 steel base metal in this test. The wear mass loss ofQ235 steel is 14 times as that of the composite coating under applied load of 40 kg.展开更多
Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by opti...Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by optical microscopy, X-Ray diffraction, SEM, TEM and microhardness tester. The results show that the interface between the coating and the substrate is metallurgically bonded. The coating was uniform and almost defect-free when [Ti+C] varied from 10% to 20% after ball milling. The microstructure of the coating is mainly composed of -Ni dendrite, interdendritic eutectic ( -Ni austenite, M23C6 and CrB) and TiC particles. Most of the TiC particles are spherical and a small fraction is blocky in size of l^2(im. The TiC particles are smaller at the bottom than near the top of the coating. The coating has a gradient microstructure and a highest hardness of lOOOHyO. 1.展开更多
A new type oxidation resistance in situ Cr7 C3/γ-Fe ceramic composite coating was fabricated on hardened and tempered grade C steel by reactive plasma clad with Fe-Cr-C alloy powders. The oxidation resistance of the...A new type oxidation resistance in situ Cr7 C3/γ-Fe ceramic composite coating was fabricated on hardened and tempered grade C steel by reactive plasma clad with Fe-Cr-C alloy powders. The oxidation resistance of the ceramic composite coating was investigated under the test condition of 900 ℃ and 50 hours. The results indicate that the coating has a rapidly solidified microstructure consisting of blocky primary Cr7 C3 and the inter-blocky Cr7 C3/γ-Fe eutectics and is metallurgically bonded to the hardened and tempered grade C steel substrate. The high temperature oxidation resistance of the coating is up to 1.9 times higher than that of grade C steel. The oxidation kinetics curve of the coating is conforming to the parabolic-rate law equation. The excellent oxidation resistance of the coating is mainly attributed to the continuous oxide films which consist of Cr203 and Fe203. The continuous oxide films can prevent the inner part of the coating from being further oxidized.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
基金Supported by Natural Science Foundation of Shandong Province （No. ZR2011EMM017 ）.
文摘Fe-Cr-Ti-C composite powder was synthesized by precursor carbonization-composition process using the mixture of ferrotitanium, chromium, iron powder and precursor sucrose as raw material. And then the Fe-Cr-Ti-C coating was prepared by reactive plasma cladding method. Microstructure of the samples was observed by scanning electron microscope （SEM）, the phases were determined by X-ray diffraction （XRD）, and the wear resistance was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the composite coating consists of primary austenite and dendritic eutectic austenite, chrysanthemum-shaped eutectic （Cr, Fe ） 7 C3 and TiC carbide. TiC presents the gradient distribution and different shapes in the coating, corresponding to equiaxial structure both in fusion zone and central zone, while it presents dendritic structure on the surface, respectively. The wear mass loss is insensitive to load for the coating while it increases rapidly for Q235 steel base metal in this test. The wear mass loss ofQ235 steel is 14 times as that of the composite coating under applied load of 40 kg.
文摘Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by optical microscopy, X-Ray diffraction, SEM, TEM and microhardness tester. The results show that the interface between the coating and the substrate is metallurgically bonded. The coating was uniform and almost defect-free when [Ti+C] varied from 10% to 20% after ball milling. The microstructure of the coating is mainly composed of -Ni dendrite, interdendritic eutectic ( -Ni austenite, M23C6 and CrB) and TiC particles. Most of the TiC particles are spherical and a small fraction is blocky in size of l^2(im. The TiC particles are smaller at the bottom than near the top of the coating. The coating has a gradient microstructure and a highest hardness of lOOOHyO. 1.
文摘A new type oxidation resistance in situ Cr7 C3/γ-Fe ceramic composite coating was fabricated on hardened and tempered grade C steel by reactive plasma clad with Fe-Cr-C alloy powders. The oxidation resistance of the ceramic composite coating was investigated under the test condition of 900 ℃ and 50 hours. The results indicate that the coating has a rapidly solidified microstructure consisting of blocky primary Cr7 C3 and the inter-blocky Cr7 C3/γ-Fe eutectics and is metallurgically bonded to the hardened and tempered grade C steel substrate. The high temperature oxidation resistance of the coating is up to 1.9 times higher than that of grade C steel. The oxidation kinetics curve of the coating is conforming to the parabolic-rate law equation. The excellent oxidation resistance of the coating is mainly attributed to the continuous oxide films which consist of Cr203 and Fe203. The continuous oxide films can prevent the inner part of the coating from being further oxidized.
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.
