Copper-titanium diboride coatings obtained by plasma spraying reactive micropellets

Electrotribological applications require materials with both high electrical conductivity and wear resisance. For this purpose, a copper- base plasma sprayed coating containing titanium diboride particles was developed. The process for fabricating this CU- TiB₂ coating consists of plasma spraying reactive powders that contain a Cu- Ti alloy and boron. The reaction between the copper alloy and boron proceeds in different steps going from solid- state diffusion of titanium and copper to the synthesis of TiB₂ in a liquid below 1083 ‡C. Plasma sprayed copper coatings contain finer TiB₂ crystals than Cu- TiB₂ materials synthesized in a furnace at 1200 ‡C. Coatings with 25 vol% TiB2 have hardnesses that are comparable to Cu- Co- Be and Cu- Ni- Be alloys and to Cu- W and Cu- Mo alloys used in spot welding. Their low electrical resistivity of 52 ΜΩ cm could be increased by lowering the oxygen content with coatings and controlling the formation of TiB₂ clusters, the titanium content in solution in copper remaining low after the synthesis reaction.     

大气等离子喷涂TiB2-316L不锈钢基复合涂层及其耐磨性能

分别采用高能球磨制备了TiB2含量(质量分数)为10%的316L不锈钢基复合粉,高能球磨与喷雾干燥造粒工艺制备了TiB2含量(质量分数)为40%的316L不锈钢基复合粉,大气等离子喷涂制备相应的TiB2-316L不锈钢基金属陶瓷涂层与316L不锈钢涂层.室温下采用高速环块磨损试验研究TiB2-316L不锈钢基金属陶瓷涂层的磨损特性.采用X射线衍射分析涂层物相,扫描电镜分析喷涂粉末、涂层结构和摩擦副磨损表面形貌.结果表明,大气等离子喷涂两种制粉工艺获得的316L不锈钢基TiB2复合粉能获得较耐磨的316L不锈钢基TiB2复合涂层,耐磨性高于316L不锈钢涂层,且TiB2在复合涂层中增强涂层耐磨性的原因是TiB2颗粒在涂层316L韧性基体中充当强化相,且TiB2在摩擦接触处摩擦氧化形成的氧化产物具有自润滑特性,能减少涂层的磨损量.