Wear Loss Evaluation of Silicon Nitride-Hexagonal Boron Nitride Composite using Taguchi Method

Biomaterials in body environment are expected to work satisfactorily, where the pH value of body fluid varies from 1 to 9. Friction, wear, and lubrication of artificial joints are an important consideration to optimise the performance of these man-made joints to improve its function and life. The first metal-on-metal (CoCr-CoCr) total hip replacement (THR) was unsatisfactory because of high friction forces and high rate of wear. Titanium alloys and stainless steel are frequently used in THR. The main risk with metal alloy implants is the release of metal ions due to wear and which creates an adverse effect like aseptic loosening. Therefore metal-on-UHMWPE bearing became advantages or preferable to the metal-on-metal system. Ceramic bearings were first introduced as alternatives to polyethylene (PE) bearings in THR about a decade after Sir John Charnley introduced the first durable THR with a metal-PE articulation. In 1965, the first Al2O3 material dedicated for hip joint was patented, and pioneering application of bio-ceramic was replacing traditional metallic femoral heads of hip prostheses using high density and pure alumina. The Al2O3 and ZrO2 like oxide have a lengthy history in the field of hip and knee joint replacement providing a tougher bearing surface with low wear rate. Initially, in the engineering field, Si3N4 was proposed as a substitute for conventional materials in extreme operating conditions, due to its hardness, excellent chemical and stability under a broad range of temperature, low density, low thermal expansion, high specific stiffness, corrosion resistance, high elastic modulus and low friction properties [1]. Biocompatibility and material properties of Si3N4 have made it attractive alternative in the biomedical field also [2]. Bearings made of ceramics have low wear properties that make them a suitable alternative for total hip arthroplasty (THA) and total knee arthroplasty (TKA). When compared to cobalt chrome (CoCr)-on-polyethylene (PE) articulations, ceramics offer drastic reductions in bearing wear rates. Alumina and zirconia ceramics are familiar with the orthopaedic field in total joints for several decades [3]. Currently, Si3N4 is applicable in the biomedical field for various applications like bearing for