Integrated Experimental Approach for Alloying of Surface Layer Ti6Al4V+B4C Metal Matrix Composites using Laser Treatment

Surface engineering applications have brought the titanium and its alloys into the limelight in the manufacturing industries such as the aerospace, automobile, marine, chemical processing industry, nuclear power and biomedical. Despite the growths experienced in the use of this material, it is plagued with poor wear behaviour, especially when in contact with other materials during application. In this research work, the reinforcement of titanium alloy (Ti6Al4V) and boron carbide (B4C) ceramic powders was employed to form the Ti6Al4V+B4C composites. The effect of laser power on the micrograph, microhardness, surface roughness and wear has been investigated. The micrographic evaluation, the geometrical analyses and the effect of laser power on the width and height of deposit, aspect ratio and dilution rate were also evaluated. The highest aspect ratio of 5.31 and dilution rate of 63.81 % was observed in sample MB5 deposited with a laser power of 2400 W. The dry sliding friction and wear conducted using a 10 mm diameter tungsten carbide ball and a normal load of 25 N revealed that sample MB2 produced at a laser power of 1800 W has the lowest wear depth and wear width of 74.6 µm and 1080.77 µm. From the lowest COF attributed by sample MB5, it can be inferred that coefficient of friction does not determine the wear loss due to the sticking of some wear debris to the wear track during sliding action. Thus, other wearing factors are also considered for the wear loss evaluation. However, this composite can be used for the repair of the worm part of a rotating shaft and turbine blades.

表面工程应用使得钛及其合金在航空航天、汽车、船舶、化工、核电以及生物医学等制造领域备受瞩目。尽管该材料的应用规模持续扩张，但其耐磨性能欠佳的缺陷始终存在，尤其在应用过程中与其他材料接触时更为显著。本研究采用钛合金（Ti6Al4V）与碳化硼（B4C）陶瓷粉末进行复相增强，制备得到Ti6Al4V+B4C复合材料，探究了激光功率对试样显微形貌、显微硬度、表面粗糙度以及磨损行为的影响。此外，本研究还开展了显微形貌表征、几何参数分析，并考察了激光功率对熔覆层宽度、高度、宽高比以及稀释率的作用规律。当激光功率为2400 W时制备的MB5试样，其宽高比可达5.31、稀释率达63.81%，为所有试样中的最高值。采用直径10 mm的碳化钨球作为摩擦副、施加25 N法向载荷开展干滑动摩擦磨损试验后发现，激光功率1800 W制备的MB2试样磨损深度与磨损宽度最低，分别为74.6 µm与1080.77 µm。MB5试样的摩擦系数（Coefficient of Friction，COF）最低，由此可推断：滑动过程中部分磨屑粘附于磨损轨迹时，摩擦系数并非决定磨损量的唯一因素。因此，在开展磨损量评估时，还需综合考量其他磨损影响因素。不过，该复合材料可用于旋转轴蜗杆部件与涡轮叶片的修复作业。