采用综合热分析仪对冷喷涂铬锆铜合金涂层进行了示差扫描热(DSC)分析,并利用激光共焦扫描高温成像显微镜对其组织在加热过程中的演变进行了原位观察,测试了退火前后涂层的硬度.结果表明:涂层在加热过程的DSC曲线上有三个峰,分别对应涂层的变形组织回复阶段、再结晶形核与晶粒长大阶段、内部颗粒界面消失阶段;经过前两阶段后涂层的显微硬度从159.69 HV逐渐降至77.57 HV;第三阶段显微硬度变化不大,与烧结工艺中颗粒界面融合过程相似;加热至350℃时涂层显微组织未发生变化,至550℃时涂层组织具有原始粉体的等轴晶形貌,至900℃时涂层组织颗粒界面逐渐均一化,与原始粉体相近.
Thermal changes of the cold-sprayed CrZrCu coating were studied by differential scanning calorimetry. With the aid of high-temperature laser scanning microscope the in-situ observation of microstructure evolution in annealing process had been made, and the hardnesses of the coating before and after annealing were tested. The results indicate that there were three peaks on the DSC curve of the coating during heating process,which corresponded to deformed stages of recovering process, recrystallization nucleation and grain growth, and particle interface meniscus-disappearing respectively. Microhardness of the coating declined from 159. 69 HV to 77. 57 HV in the first two stages, but kept stable in the third stage which was similar to the integration of particle boundaries in sintering. The microstructure did not change after 350 ℃ annealing, it turned into equiaxed crystal when the temperature increased to 550 ℃, at 900 ℃, grain structure of CrZrCu coating became homogeneous,corresponding to the structure of original powder.
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