钛合金氧碳共渗层性能

Performance of Oxygen-Carbon Co-cementation Coating on Titanium Alloy

摘要:

将经磨平、抛光、超声波乙醇清洗、吹干的Ti6Al4V合金样品放入专用设备中进行氧碳共渗。分别采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、能谱仪（EDS）、HV硬度仪、万能材料试验机对渗层的物相、显微组织形貌、成分、硬度、摩擦磨损、力学性能进行分析。XRD结果表明，渗层中出现TiC和TiO_x相。氧碳共渗改变了原Ti6Al4V合金的组织，渗层的显微组织明显区别于Ti6Al4V的渗碳、渗氧以及在CO₂气氛下处理的组织。EDS结果表明，C、O元素含量呈现梯度变化。相比基体硬度，渗层表面硬度提高了3.8倍，渗层硬度呈梯度变化。氧碳共渗改变了原始样的粘着磨损和摩擦状态，渗层样表面只有轻微的摩擦痕迹、无磨损。氧碳共渗后磨损量是原始样的3.5%，摩擦系数约为原始样的30%。渗层样在拉断过程中，外表面有一定的剥落，表面布满裂纹，样品的强度略有下降，断面延伸率和断面收缩率与原始样相当。Ti6Al4V合金经过氧碳共渗后，提高了表面硬度，降低了磨损率和摩擦系数，基本保持了基体的力学性能。

Abstract:

The Ti6Al4V alloy specimens were planished, polished, cleaned by ethyl-alcohol with ultrasonic, and dried. Then, the treated specimens were put into a special equipment for oxygen-carbon co-cementation. The X-ray diffractometer (XRD), scanning electron microscope (SEM), energy disperse spectroscope (EDS), HV hardness tester, and universal material testing machine were used to analyze the phase, microstructure, composition, hardness, frictional wear, and mechanical properties of the co-cemented layer. XRD results show that TiC and TiO_x phases appear in the co-cemented layer. The microstructure of the original Ti6Al4V alloy specimen is changed by the oxygen-carbon co-cementation. The microstructure of the co-cemented layer is obviously different from that of Ti6Al4V alloy specimens after carburization treatment, oxygen permeation treatment, and treatment under CO₂ atmosphere. EDS results show that the content of C and O elements changes gradually. The surface hardness of the co-cemented layer is 3.8 times higher than that of the substrate, and the hardness of the co-cemented layer also changes gradually. The oxygen-carbon co-cementation changes the adhesive wear and friction state of the original specimen. Only slight friction trace occurs on the surface of the co-cemented specimen and no wear appears. The wear amount of the co-cemented specimen is 3.5% of that of the original specimen, and the friction coefficient is about 30% of that of the original specimen. In the tensile fracture process, the outer surface of the co-cemented specimen peels off to a certain extent, and the surface is covered by cracks, resulting in the slightly decreased strength of the specimen. The elongation and the reduction of area are comparable to those of the original specimen. After oxygen-carbon co-cementation of Ti6Al4V alloy, the surface hardness of the specimen is improved, the wear rate and friction coefficient are reduced, and the mechanical properties of the specimens basically remain.