纳米SiC含量对激光熔覆镍基合金组织性能影响

采用预置式,在45^#钢基体表面,铺设0.8 mm厚度的纳米SiC增强NiFeBSi复合合金粉末。利用3 kW横流CO₂激光,熔覆不同增强比例的复合涂层。利用X射线衍射（XRD）仪,扫描电镜（SEM）、显微硬度仪、摩擦磨损试验机分别对不同增强比例涂层进行微观组织、力学性能的分析及讨论。探究了纳米SiC含量对熔覆层组织性能的影响。研究结果表明,NiFeBSi+纳米SiC复合涂层具有与NiFeBSi合金涂层相似的组织形貌特征,在激光熔覆过程中纳米SiC颗粒的分解,致使γ（Fe,Ni）枝晶间上形成了多种碳化物。因此,显著提高了NiFeBSi合金涂层的硬度,并随着纳米SiC的掺入量增多,硬度提高显著。纳米SiC的加入显著地增强了熔覆层的耐磨性能,但随含量增加磨痕表面产生脆性变形和裂纹,其中NiFeBSi+w（SiC）=7%复合涂层的耐磨性能最好。

Influence of Nano-SiC Content on Microstructure and Properties of Laser Clad NiFeBSi Alloy Coating

Nano-size reinforced NiFeBSi composite alloy powders were laid on 45 steel with the thickness of 0.8mm using presettingtechnique. Different proportions of composite coatings were cladded with the 3.0kW crossflow CO2 laser. Both microstructure and mechanical property of each coating were studied and discussed by means of x-ray diffractometer(XRD), scanning electron microscope(SEM),microhardness tester and friction and wear tester, for the influence of the content of nano SiC on the cladding layer structureproperty. The results show that the NiFeBSi + nano SiC composite coating has the similar structural morphology feature with theNiFeBSi alloy coating. Nano SiC particles are decomposed during the cladding process, resulting in the formation of several carbidesamong the酌 (Fe,Ni) dendrites. The hardness of NiFeBSi alloy coating is therefore improved and would obviously be further enhancedwith the increasing amount of SiC incorporation, which significantly enhances the wear resistance of the cladding layer. The brittledeformation and crack, however, appear with the increasing nano SiC content, concluding that the NiFeBSi＋7wt.%SiC composite coating should have the best wear resistance performance.