Study On Mechanical Property And Corrosion Behavior Of Co-Cr Alloy Fabricated By Laser Rapid Forming Technology

Cobalt-chromium alloy because of its excellent biocompatibility, fatigueresistance strength, high mechanical strength and low price has become one ofthe most widely used oral alloys in our country. However, investment castingwhich is commonly used method of making metal dental prostheses can notmeet the requirements of doctors and patients for having the fast, personalizeddental treatments. As a new metal fabricating technology,Laser Rapid Forming(LRF) overcomes the shortcomings of traditional technique and significantlyimproves the efficiency of the production of dental prosthesis and its quality.In this study, our objective aims to find the suitable parameters forfabricating Co-Cr alloy by Laser Rapid Forming (LRF) technique and toinvestigate the microstructure, mechanical properties and corrosion behaviorof LRF Co-Cr.The contents and methods of this study can be described as follows: First, the LRF Co-Cr alloy was fabricated by LRF with suitable parameters(Laserpower, 2000W; Powder feeder rate,6.5g/min; Scan speed, 300mm/min; Spotdiameter, 3mm)and then the chemical composition, microstructure, tensileproperties,microhardness, and thermal expansion coefficient (TEC) of thesamples were analysis. The results were then compared with that of the castCo-Cr alloy with same chemical composition by one group t-test. Second,static immersion test and electrochemical test were used to evaluate thecorrosion behavior of LRF Co-Cr alloy and cast Co-Cr alloy.The result is that: The tensile strength, yield strength, Vickers hardness andYoung's modulus of LRF Co-Cr alloy are higher than those of the cast Co-Cralloy. While the elongation of LRF Co-Cr alloy is lower than that of cast Co-Cr alloy (p?0.05). There is no significant statistical difference between theTEC of the two alloys (p?0.05). Static immersion test showed that: in the threesolutions, the Co,Cr,Mo,W ions releasing from LRF Co-Cr alloy were lessthan the cast ones. Electrochemical test showed that comparing to the cast Co-Cr alloy, the LRF Co-Cr alloy's free corrosion potential was higher, the freecurrent density was lower and the film resistance were higher in the threesolutions. Both of the tests showed better corrosion resistance of the LRF Co-Cr alloy.A conclusion can be drawn that: These experimental results show thatLRF cobalt-chromium alloy's mechanical strength and corrosion resistance aresuperior to cast one's. LRF Co-Cr alloy is a novel alloy with excellentproperties and shows a good potential in clinical applications.