Abstract
We examined the chemical, physical, and mechanical properties and microstructures of laser-sintered Co–25Cr–5Mo–5W (SP2) and W–free Co–28Cr–6Mo alloys. The tensile and fatigue properties of the laser-sintered Co–Cr–Mo alloys were extremely superior to those of dental-cast alloys. The ultimate tensile strength (σUTS) and total elongation (T.E.) were close to those of hot-forged Co–28Cr–6Mo alloys. The fatigue strengths (σFS) at 107 cycles of the 90°-, 45°-, and 0°-direction-built Co–28Cr–6Mo alloys were ~500, ~560, and ~600 MPa, respectively. The ratio σFS /σUTS was ~0.4. These superior mechanical properties were attributed to the fine π-phase particles in the grains and grain boundaries of the fine face–centered cubic (fcc) matrix formed owing to the rapid solidification. The chemical composition of 20-times-laser-sintered Co–Cr–Mo alloy without the virgin powder added was approximately the same as that of the alloy laser-sintered with the virgin powder. σFS of the 90°-direction-built alloys after laser sintering 20 times was also ~500 MPa. σUTS of hot-forged Co–28Cr–6Mo alloys decreased with increasing annealing temperature, whereas T.E. increased. For the Co–Cr–Mo alloys annealed at 1000 to 1150 °C for 30 min after laser sintering, the rates of decrease in σUTS were small. σFS/σUTS increased to near those of annealed Co–28Cr–6Mo alloys after hot forging. The durability of clasps fabricated by laser sintering was superior to that of dental-cast clasps.
Highlights
Dental prostheses require biomechanical compatibility as well as biological safety
The chemical composition of 20-times-laser-sintered Co–Cr–Mo alloy without the virgin powder added was approximately the same as that of the alloy laser-sintered with the virgin powder. σFS of the 90◦ -direction-built alloys after laser sintering 20 times was ~500 MPa. σUTS of hot-forged
We evaluated the chemical composition, physical properties, immersion property, microstructure, tensile property, and fatigue strength of laser-sintered Co–25Cr–5Mo–5W (SP2) and
Summary
Dental prostheses require biomechanical compatibility as well as biological safety. Cobalt–chromium–molybdenum (Co–Cr–Mo) alloys with excellent mechanical properties and structural stability have been widely used for dentures, metal frames, bridges, partial dentures, complete dentures, and implant superstructures in dentistry. Co–Cr–Mo alloys have been used for total hip and knee replacements in orthopedics, with both cast and wrought materials used. Co–Cr–Mo alloys are essential for medical applications and have been standardized by the International Organization for Standardization (ISO) [1,2], American Society for Testing and Materials (ASTM) [3,4], and Japanese. Industrial Standards (JIS) [5,6,7]. Computer–aided design and computer–aided machining (CAD/CAM) technology has rapidly improved with the remarkable development of digital technology.
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