口腔修复中选区激光熔化工艺及性能研究

The Study of Technology and Properties of Selective Laser Melting in Prosthodontics

为实现医用钴铬合金在口腔修复中的应用,利用选区激光熔化(SLM)技术,研究开发了激光选区熔化成型工艺并进行了弯曲、拉伸、硬度以及热处理实验。利用扫描电镜、粗糙度轮廓仪、硬度仪等检测手段,对激光选区成型的试件进行了显微组织、力学性能、粗糙度、腐蚀性能等测试分析。研究结果表明,激光选区熔化成型最佳工艺参数为激光功率200 W、扫描速度500mm/s、层厚25μm、扫描间距0.07mm及扫描策略为S型X、Y方向、层错;SLM原始试样抗拉强度为1 185MPa、硬度为431HV、延伸率为8.6%、断裂形式为准解理断裂,热处理后抗拉强度为1 375MPa、硬度为563HV、伸长率为3.1%;SLM原始试样自腐蚀电位为-717mV、自腐蚀电流密度为1.7×10^(-5) A/cm^2,热处理后自腐蚀电位为-10mV、自腐蚀电流密度为0.3×10^(-5) A/cm^2;SLM原始样粗糙度为13.793μm、表面重熔后粗糙度降为5.141μm,打磨后粗糙度降为2.24μm。因此,热处理能提高试样的强度和耐腐蚀性,但韧性有所降低。最后利用优化的工艺参数,选区激光熔化成型制备出高强度、低粗糙度和耐腐蚀的牙冠牙桥,并进行佩戴实验,基本符合义齿的性能要求。

In order to realize the application of medical cobalt-chromium alloy in prosthodontics, using Selective Laser Melting （SLM） technology, the laser forming process was studied and developed, and the bending, tensile, hardness and heat treatment experiments were carried out. Using SEM, roughness profiler, hardness tester and other means of detection, the microstructures, mechanical properties, roughness and corrosion properties of the specimens were analyzed. Research shows the optimum parameters of SLM are as follows： laser power was 200 W, scanning speed was 500 mm/s, slice thickness was 25 μm, scanning distance was 0.07 mm and scanning strategy was S-type X, Y, stacking fault; SLM original sample tensile strength of 1 185 MPa, hardness of 431 HV, elongation of 8.6%, fracture in the form of quasi-cleavage fracture, the tensile strength after heat treatment was 1 375 MPa, the hardness was 563 HV, the elongation was 3. 1%. The corrosion potential of SLM was -- 717 mV, and the corrosion current density was 1.7 × 10^-5 A/cm^2 , The corrosion potential was - 10 mV and the corrosion current density was 0. 3 × 10^-5 A/cm^2 after heat treatment. The roughness of SLM was 13. 793 μm, after surface remelting, the roughness decreased to 5. 141 μm, and the roughness decreased to 2.24 μm after grinding. Therefore, the heat treatment can improve the strength and corrosion resistance of the sample, but the toughness is reduced. Finally, the tooth crown bridge with high strength, low roughness and corrosion resistance was fabricated by SLM with optimized process parameters, and the wearing experiment was carried out, which accords with the performance requirements of the denture.