Parameter Optimization of Sintering Ti-6Al-7Nb Powder for the Minimum Shrinkage and the Highest Surface Roughness Using Taguchi Method

Abstract

The usage of a higher biocompatibility titanium niobium (Ti-6Al-7Nb) has enhanced mechanical properties to prevent stress shielding and consecutive implant loosening due to inadequate load transfer. However, the presence of vanadium with toxic element in the alloy Ti-6Al-7V is concerned as deterioration or corrosion could occur. The alternative titanium alloy such as Ti-6Al-7Nb and Ti-5Al-2.5Fe was produced to replace Ti-6Al-7V alloy due to its toxicity issue. The objective of this paper is to investigate the influence of sintering parameter for Metal Injection Moulding (MIM) process on the mechanical properties of Ti-6Al-7Nb such as shrinkage and surface roughness. The Taguchi’s orthogonal array, L9 (3⁴) were used for analyzing the effect of each parameter on the mechanical properties and to predict the optimal setting for each sintering parameter. The optimum sintering parameter for shrinkage is sintering temperature at 1200 ℃, holding time for 5 h, heating rate at 4 ℃ per minute and cooling rate at 5 ℃ per minute where the result shows between 6.59 and 6.85% of shrinkage. Lastly, the required optimum sintering parameter for surface roughness are the sintering heating temperature at 1250 ℃, holding time for 4 h, heating rate at 4 ℃ per minute and cooling rate at 5 ℃ per minute where the range of surface roughness result is between 2.10 µm and 2.81 µm. The result for both experiments are acceptable as the percentage error for both shrinkage and surface roughness are 7.72 and 9.76%, respectively which are below than 10%.