title: Calcium phosphate-titanium composites for articulating surfaces of load-bearing implants.
abstract: Calcium phosphate (CaP)-titanium (Ti) composites were processed using a commercial laser engineered net shaping (LENS™) machine to increase wear resistance of articulating surfaces of load-bearing implants. Such composites could be used to cover the surface of titanium implants and potentially increase the lifetime of a joint replacement. It was hypothesized that adding calcium phosphate to commercially pure titanium (CP-Ti) and Ti6Al4V alloy via laser processing would decrease the material loss when subjected to wear. This added protection would be due to the in situ formation of a CaP tribofilm. Different amounts of CaP were mixed by weight with pure Ti and Ti6Al4V powders. The mixed powders were then made into cylindrical samples using a commercial LENS™-750 system. Microstructures were observed and it was found the CaP had integrated into the titanium metal matrix. Compression test revealed that CaP significantly increased the 0.2% offset yield strength as well as the ultimate compressive strength of CP-Ti. It was found that the addition of CaP to pure titanium reduced the material loss and increased wear resistance. This was due to the formation of CaP tribofilm on the articulating surface. The in situ formed tribofilm also lowered the coefficient of friction and acted as a solid lubricant between the two interacting metal surfaces. Overall, CaP addition to Ti and its alloy Ti6Al4V show an effective way to minimize wear induced damage due to the formation of in situ tribofilm at the articulating surface, a strategy that can be utilized in various biomedical devices.
authors.affiliation: W. M. Keck Biomedical Materials Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA. Electronic address: amitband@wsu.edu.
authors.forename: Amit
authors.initials: A
authors.lastname: Bandyopadhyay
authors.affiliation: W. M. Keck Biomedical Materials Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Dittrick
authors.affiliation: W. M. Keck Biomedical Materials Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gualtieri
authors.affiliation: W. M. Keck Biomedical Materials Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Wu
authors.affiliation: W. M. Keck Biomedical Materials Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
authors.forename: Susmita
authors.initials: S
authors.lastname: Bose
mesh_terms: D000497:Alloys; D002130:Calcium Phosphates / Q000737:chemistry*; D008422:Materials Testing; D019736:Prostheses and Implants; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D016474:Weight-Bearing
chemical_list: D000497:Alloys; D002130:Calcium Phosphates; C031462:titanium alloy (TiAl6V4); C020243:calcium phosphate; D014025:Titanium
keywords: Calcium phosphate–Ti composites; Load-bearing implants; Metal ion release; Tribofilms; Wear resistance