L.Q. Ren

Statistical wear analysis of PA-6/UHMWPE alloy, UHMWPE and PA-6

This paper, based on an orthogonal experimental design and analysis method, reports the wear of a blend of polyamide-6/ultrahigh molecular weight polyethylene (PA-6/UHMWPE), using a pin-on-disc test, and rubbing against a stainless steel counterface. The wear behavior of PA-6 and UHMWPE was also investigated for the purpose of comparison. The main purpose was to study the influence of the parameters: sliding distance, contact pressure and sliding speed on the wear performance of the investigated materials. Statistical analysis was carried out to develop an equation in which the wear volume of the specimen was expressed in terms of sliding distance, contact pressure and sliding speed. It was observed that the wear rate was lower for PA-6 than the other two materials. UHMWPE exhibited the lowest wear resistance. Contact pressure was found to be the most important factor in the wear of materials, followed by sliding distance and sliding speed. Sliding distance had the highest relative effect on the wear of PA-6/UHMWPE. Sliding speed seemed to have the least effect on the wear volume of the investigated materials. The results show that the wear behavior of these materials, and the effects of factors on the wear, depend on the physical and mechanical properties of the materials.

Effects of operating parameters on the lubricated wear behavior of a PA-6/UHMWPE blend: a statistical analysis

In this paper, based on an orthogonal test design and analysis method, the lubricated wear performance of a ultra-high molecular weight polyethylene and polyamide (PA-6/UHMWPE) alloys were studied using a pin-on-disc method. The effects of several parameters on the wear of the PA-6/UHMWPE alloy, rubbing against a stainless steel counterface, are reported. The main purpose was to study the influence of parameters such as sliding distance, counterface surface roughness, load and sliding speed, as well as their interactions on the wear performance. Statistical analysis was carried out to develop an equation, in which the wear volume of the polymeric specimen was expressed in terms of the investigated parameters. It was observed that the pressure and surface roughness are the two important and controlling factors; sliding distance and sliding speed have a minor effects on the wear of the specimens. Although the two-factor and three-factor interactions have little effect, the four-factor interaction has a strong effect on the wear of specimens. The results give a comprehensive insight into the wear of the PA-6/UHMWPE alloy.

Bioinspired surface functionalization of metallic biomaterials

Metallic biomaterials are widely used for clinical applications because of their excellent mechanical properties and good durability. In order to provide essential biofunctionalities, surface functionalization is of particular interest and requirement in the development of high-performance metallic implants. Inspired by the functional surface of natural biological systems, many new designs and conceptions have recently emerged to create multifunctional surfaces with great potential for biomedical applications. This review firstly introduces the metallic biomaterials, important surface properties, and then elaborates some strategies on achieving the bioinspired surface functionalization for metallic biomaterials.

Reactive deposition of aluminium oxide coatings on PTFE substrate

Aluminium oxide coatings were deposited on to polytetrafluoroethylene (PTFE) substrates by the reactive sputtering technique in a closed-field unbalanced magnetron sputtering (CFUBMS) system. The effects of sputtering parameters on wear performance and on the structure of the coatings were investigated. The resulting coatings were analysed by microanalyser, scanning electron microscope (SEM) and a ball-on-disc wear test. Depending on the preparation conditions, the coatings were shown to have different compositions and different mechanical properties. The results revealed that ductile, dense coatings could be obtained in a low oxygen concentration plasma, while a high oxygen concentration in the plasma results in a granular, porous structure to the coatings. The coatings with a medium Al/O ratio exhibited good wear and impact resistance; high Al/O ratio coatings adhere to the substrate well and possess good impact resistance, but have low wear resistance; and low Al/O ratio coatings possess poor impact resistance, and are prone to cracking and debonding of the coating due to substrate yielding during a ball-on-disc wear test.