A comparison of corrosion resistance of cobalt-chromium-molybdenum metal ceramic alloy fabricated with selective laser melting and traditional processing.
BACKGROUND
A cobalt-chromium-molybdenum alloy fabricated by selective laser melting is a promising material; however, there are concerns about the change in its corrosion behavior.


OBJECTIVE
The purpose of this study was to evaluate the changes in corrosion behavior of a cobalt-chromium-molybdenum alloy fabricated by the selective laser melting technique before and after ceramic firing, with traditional processing of cobalt-chromium-molybdenum alloy serving as a control.


METHODS
Two groups of specimens were designated as group selective laser melting and group traditional. For each group, 20 specimens with a cylindrical shape were prepared and divided into 4 cells: selective laser melting as-cast, selective laser melting fired in pH 5.0 and 2.5, traditional as-cast, and traditional fired in pH 5.0 and 2.5. Specimens were prepared with a selective laser melting system for a selective laser melting alloy and the conventional lost wax technique for traditional cast alloy. After all specimen surfaces had been wet ground with silicon carbide paper (1200 grit), each group of 10 specimens was put through a series of ceramic firing cycles. Microstructure, Vickers microhardness, surface composition, oxide film thickness, and corrosion behavior were examined for specimens before and after ceramic firing. Three-way ANOVA was used to evaluate the effect of porcelain firing and pH values on the corrosion behavior of the 2 alloys (α=.05). Student t tests were used to compare the Vickers hardness.


RESULTS
Although porcelain firing changed the microstructure, microhardness, and x-ray photoelectron spectroscopy results, it showed no significant influence on the corrosion behavior of the selective laser melting alloy and traditional cast alloy (P>.05). No statistically significant influence was found on the corrosion behavior of the 2 alloys in different pH value solutions (P>.05).


CONCLUSIONS
The porcelain firing process had no significant influence on the corrosion resistance results of the 2 alloys. Compared with traditional cast cobalt-chromium-molybdenum alloy, selective laser melting alloy exhibited the same properties in both test solutions (pH, 5.0 or 2.5).
Intern, Department of Prosthodontics, Stomatology Special Consultation Clinic, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
Li
L
Zeng
Intern, Department of Prosthodontics, Stomatology Special Consultation Clinic, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
Nan
N
Xiang
Associate Professor, Department of Prosthodontics, Stomatology Special Consultation Clinic, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. Electronic address: weibin0328@hotmail.com.
Bin
B
Wei
D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry*; D003343:Corrosion; D003735:Dental Casting Technique / Q000295:instrumentation; D003775:Dental Polishing / Q000379:methods; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007834:Lasers; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D011048:Polarography; D011199:Potentiometry; D012464:Saliva, Artificial / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014618:Vacuum
D017554:Carbon Compounds, Inorganic; D002858:Chromium Alloys; D016876:Metal Ceramic Alloys; D010087:Oxides; D012464:Saliva, Artificial; D017655:Silicon Compounds; C022088:silicon carbide