采用高功率横流CO2激光扫描钎料合金与金刚石颗粒。研究了激光工艺参数对钎焊层结合性能及金刚石热损伤的影响,分析了钎焊层与金刚石结合机制及金刚石颗粒在激光作用下的热损伤机制。研究结果表明,激光功率和扫描速度是影响金刚石热损伤及表面浸润的主要因素。在氩气保护下,粉末厚度为0.5 mm,激光光斑直径3 mm,功率为800 W,扫描速度为8.39 mm/s时,可获得金刚石颗粒、钎料合金、金属基体三者具有最佳结合性能的钎焊层。合金粉末对金刚石颗粒浸润良好,并发生冶金化学反应,生成TiC和SiC。当激光输入能量太高时,金刚石颗粒开始与外界的氧发生氧化反应,在自由能方程中的气体分压下,金刚石一直氧化,直到与氧化物处于平衡状态。这一过程表现为金刚石颗粒石墨化,逐步氧化烧损变成气体。

High power transverse flow CO2 laser was used to scan the brazing alloy and diamond grits. The influence of laser technological parameters on brazing layer combination performance and diamond grits thermal damage was researched, and the thermal damage mechanism of laser brazed diamond and the combination mechanism of brazing layer and diamond grits were analyzed. The research results showed that laser power and scanning speed were the main factors for diamond thermal damage and surface wetting. On the conditions of 0.5 mm brazing layer thickness, argon shield, 800 W laser power, and 8.39 mm/s scanning speed, the best combination performance among the diamond grits, brazing alloy and metallic base can be achieved. Brazing alloy wetted the diamond grits well and reacted with them to form TiC and SiC. Under high laser energy input, oxidation take placed between diamond grits and oxygen outside, diamond would be oxidized all along on the condition of branch gas pressure about free equation until the balance established between diamond and oxide, during this process, diamond grits would be carbonized or burn out and gasified.