冷喷涂SiC/Al纳米复合涂层的组织结构与性能

Microstructure and Properties of Cold-sprayed SiC/Al Nanocomposite Coatings

为制备基体相晶粒细小、增强相均匀分布的SiC/Al纳米复合涂层,以Al、SiC为原料,采用高能球磨法获得SiC颗粒弥散分布的纳米晶Al基复合材料粉末,利用冷喷涂技术低温成型制备了SiC/Al纳米复合涂层,分析了SiC含量对复合涂层相结构、晶粒尺寸、微观结构、硬度及磨损性能的影响规律。结果表明:冷喷涂可实现球磨纳米晶复合粉末结构的原位移植,所制备SiC/Al纳米复合涂层组织致密,微米及亚微米级SiC弥散分布在纳米晶Al (约80 nm)基体之上;SiC颗粒对Al基体有明显强化作用,冷喷涂SiC/Al纳米复合涂层的硬度随SiC体积分数的增加而显著增加,50%SiC/Al纳米复合涂层的硬度高达515 HV0.3,约为Al块材的13倍;冷喷涂SiC/Al纳米复合涂层的耐磨损性能随着SiC含量增加而显著提高,涂层磨损失效机制为磨粒对基体的切削犁沟变形。

To prepare SiC/Al nanocomposite coating with fine grains matrix and uniformly distributed reinforcement,the SiC/Al nanocomposite powders were first produced by a high energy ball milling process using pure Al and SiC powder as raw material.SiC/Al nanocomposite coatings were then successfully fabricated by cold spraying of the above-mentioned SiC/Al nanocomposite powder based on its low-temperature forming characteristics.The influence of SiC content on the phase structure,grain size,microstructure,microhardness and wear performance of the cold-sprayed SiC/Al nanocomposite coatings were analyzed.The results show that the structure of ball-milled SiC/Al nanocomposite powder can be in-situ transplanted into the coatings by cold spraying process.The cold-sprayed SiC/Al nanocomposite coatings have dense microstructure with Al matrix grain size about 80 nm and micro/sub-micrometer scale SiC particles are uniformly distributed in the matrix.SiC particles can obviously improve the strength of Al matrix,and the microhardness of SiC/Al nanocomposite coatings significantly increases with increasing volume fraction of SiC particles.The microhardness of 50% SiC/Al nanocomposite coating reaches 515 HV0.3,which is about 13 times that of Al bulk.Abrasive wear performance of SiC/Al nanocomposite coatings increases with increasing SiC content and the wear mechanism is the micro-cut effects of abrasive particles on the soft matrix surface.