Comparison of the Structure and Properties of the Solid Co-Cr-W-Mo-Si Alloys Used for Dental Restorations CNC Machined or Selective Laser-Sintered

Abstract

Abstract The purpose of this paper is to compare the impact of selective laser-sintering (SLS) technology and computer numerical control (CNC) machining methods on the structure and properties of solid Co-Cr-W-Mo-Si alloys. Structural tests were carried out using x-ray structural analysis; energy-dispersive x-ray spectroscopy chemical composition analysis; metallographic investigations using stereoscopic, light, and scanning electron microscopes using computerized methods of quantitative metallography; and tests of tensile, bending, and compression strength. Individually designed microsamples were used, and the results were statistically processed. It was shown that if optimal conditions of SLS technology are used, it is possible to obtain a structure with a pore content of 0.1 % smaller than in the case of solid cast materials. This ensures better mechanical properties than cast materials. At the same time, it was pointed out that even minor technological errors associated with SLS technology caused a lowering of all strength properties associated with a significant increase in porosity by up to 10 %. Allowing small changes in technological conditions, including the width of the laser spot, the width of the laser beam, the allowance associated with the overlap of the laser beam, disturbances in the flow of inert gas, and uncontrolled changes in the laser power, can cause a significant reduction in strength. A plug and play approach is unacceptable. If even one layer with a thickness of 25 μm is produced in suboptimal conditions, the manufactured element cannot meet the assumed requirements. The use of SLS additive technology for the production of prosthetic components made of Co-Cr alloys is the best choice among the methods currently used in dentistry. The use of SLS technology together with the digitization of design and manufacturing processes is an important element in implementing the Dentistry 4.0 approach as part of the Industry 4.0 stage of the industrial revolution.