目的研究不同溅射功率对W-C:H涂层结构与摩擦学性能的影响。方法用非平衡磁控溅射(UBMS)+等离子体增强化学气相沉积法(PECVD),以WC靶作为溅射靶,C2H2为反应气体,通过调制溅射靶功率,在316不锈钢与Si(100)基体上制备了W-C:H系列薄膜。通...目的研究不同溅射功率对W-C:H涂层结构与摩擦学性能的影响。方法用非平衡磁控溅射(UBMS)+等离子体增强化学气相沉积法(PECVD),以WC靶作为溅射靶,C2H2为反应气体,通过调制溅射靶功率,在316不锈钢与Si(100)基体上制备了W-C:H系列薄膜。通过场发射电镜(FESEM)、X射线衍射仪(XRD)、拉曼光谱对薄膜的微观结构和成分进行了表征。用UMT-3MT多功能摩擦机对薄膜的摩擦学性能进行了分析。结果 W-C主要以β-WC1-x纳米晶的形式均匀分布在非晶碳中,并表现出(200)面择优生长。随着溅射靶功率的上升,薄膜内W含量逐渐升高,(200)面衍射峰逐渐增强,sp2含量先降低后升高。靶功率在1.4 k W时具有较好的摩擦学性能,摩擦系数为0.15,磨损率为3.92×10-7 mm^3/(N·m)。结论随着溅射靶功率逐渐升高,柱状晶逐渐变粗,涂层的致密性逐渐降低,薄膜摩擦学性能与WC含量密切相关。展开更多
Diffusion couples,WC/Co-1at.%C,V8C7/Co,and WC/Co-0.3wt.%V8C7 were constructed and annealed at temperatures ranging from 1100 to 1300℃. The concentration profile of V and W atoms in these couples were measured by EPMA...Diffusion couples,WC/Co-1at.%C,V8C7/Co,and WC/Co-0.3wt.%V8C7 were constructed and annealed at temperatures ranging from 1100 to 1300℃. The concentration profile of V and W atoms in these couples were measured by EPMA. Aided by Thermo-calc ＆ DICTRA software package,the concentration profiles of W and V in established diffusion couples were calculated by the moving boundary model according to revised dynamic parameters and MOB database,respectively. Then the concentration profile of W in Co binder during sintering WC-Co cemented carbide was simulated by the Cell model. It can provide reference for composition and sintering process design of cemented carbides with high performance. Meanwhile,the validity of revised dynamic parameters of the W-C-Co-V system is verified by the comparison of experimental and simulated results.展开更多
The influences of Ce, K and Na on the structures and properties of Fe-W-C alloy were investigated, and the idea estimating spheroidizing effect of carbides using circular degree(C.D) was put forward. The result shows ...The influences of Ce, K and Na on the structures and properties of Fe-W-C alloy were investigated, and the idea estimating spheroidizing effect of carbides using circular degree(C.D) was put forward. The result shows that eutectic carbide turns into sphericity from network after modification, carbide is refined and uniformly distributed and C.D of eutectic carbide increases. The mechanism of carbide spheroidizing was analyzed. The impact toughness and abrasion resistance of Fe-W-C obviously improve with the rise of C.D of carbides. The service life of modified Fe-W-C roll is 30% higher than that of high chromium cast iron roll, while its production cost is reduced by 30%.展开更多
Porosity is a common phenomenon and can significantly hinder the quality of the coating.Here,the pore formation mechanism and the characteristics of the single tracks of the W-C coating using directed energy depositio...Porosity is a common phenomenon and can significantly hinder the quality of the coating.Here,the pore formation mechanism and the characteristics of the single tracks of the W-C coating using directed energy deposition(DED)are systematically investigated.The forming quality of the tracks,the distribution of the pores,and the elemental distribution near the pores are analyzed by the observations of the cross-sections of the tracks.The temperature field of the melt pool is discussed comprehensively to reveal the pore formation mechanism.The results confirm that Ni and Co evaporated during the DED process due to the high temperature of the melt pool.Pores were continuously produced adjacent to the fusion line when the melt pool was about to solidify since the temperature at the solidification front was higher than the boiling point of Ni.The vaporization area at the fusion line was proposed,where Ni could also evaporate at the time the melt pool started to solidify.The relationship between the solidification rate,the size of the vaporization area and the DED parameters(laser power and scanning speed)was established to discuss the causes of severe pores above the fusion line.This work contains a practical guide to reduce or eliminate the porosity in the coating preparation process on the surface of the tungsten alloy.展开更多
文摘目的研究不同溅射功率对W-C:H涂层结构与摩擦学性能的影响。方法用非平衡磁控溅射(UBMS)+等离子体增强化学气相沉积法(PECVD),以WC靶作为溅射靶,C2H2为反应气体,通过调制溅射靶功率,在316不锈钢与Si(100)基体上制备了W-C:H系列薄膜。通过场发射电镜(FESEM)、X射线衍射仪(XRD)、拉曼光谱对薄膜的微观结构和成分进行了表征。用UMT-3MT多功能摩擦机对薄膜的摩擦学性能进行了分析。结果 W-C主要以β-WC1-x纳米晶的形式均匀分布在非晶碳中,并表现出(200)面择优生长。随着溅射靶功率的上升,薄膜内W含量逐渐升高,(200)面衍射峰逐渐增强,sp2含量先降低后升高。靶功率在1.4 k W时具有较好的摩擦学性能,摩擦系数为0.15,磨损率为3.92×10-7 mm^3/(N·m)。结论随着溅射靶功率逐渐升高,柱状晶逐渐变粗,涂层的致密性逐渐降低,薄膜摩擦学性能与WC含量密切相关。
基金the National Natural Science Foundation of China (No. 50471101)the Flan-ders-China Bilateral Project BIL 02/04.
文摘Diffusion couples,WC/Co-1at.%C,V8C7/Co,and WC/Co-0.3wt.%V8C7 were constructed and annealed at temperatures ranging from 1100 to 1300℃. The concentration profile of V and W atoms in these couples were measured by EPMA. Aided by Thermo-calc ＆ DICTRA software package,the concentration profiles of W and V in established diffusion couples were calculated by the moving boundary model according to revised dynamic parameters and MOB database,respectively. Then the concentration profile of W in Co binder during sintering WC-Co cemented carbide was simulated by the Cell model. It can provide reference for composition and sintering process design of cemented carbides with high performance. Meanwhile,the validity of revised dynamic parameters of the W-C-Co-V system is verified by the comparison of experimental and simulated results.
文摘The influences of Ce, K and Na on the structures and properties of Fe-W-C alloy were investigated, and the idea estimating spheroidizing effect of carbides using circular degree(C.D) was put forward. The result shows that eutectic carbide turns into sphericity from network after modification, carbide is refined and uniformly distributed and C.D of eutectic carbide increases. The mechanism of carbide spheroidizing was analyzed. The impact toughness and abrasion resistance of Fe-W-C obviously improve with the rise of C.D of carbides. The service life of modified Fe-W-C roll is 30% higher than that of high chromium cast iron roll, while its production cost is reduced by 30%.
文摘Porosity is a common phenomenon and can significantly hinder the quality of the coating.Here,the pore formation mechanism and the characteristics of the single tracks of the W-C coating using directed energy deposition(DED)are systematically investigated.The forming quality of the tracks,the distribution of the pores,and the elemental distribution near the pores are analyzed by the observations of the cross-sections of the tracks.The temperature field of the melt pool is discussed comprehensively to reveal the pore formation mechanism.The results confirm that Ni and Co evaporated during the DED process due to the high temperature of the melt pool.Pores were continuously produced adjacent to the fusion line when the melt pool was about to solidify since the temperature at the solidification front was higher than the boiling point of Ni.The vaporization area at the fusion line was proposed,where Ni could also evaporate at the time the melt pool started to solidify.The relationship between the solidification rate,the size of the vaporization area and the DED parameters(laser power and scanning speed)was established to discuss the causes of severe pores above the fusion line.This work contains a practical guide to reduce or eliminate the porosity in the coating preparation process on the surface of the tungsten alloy.
