Abstract
D.Phil. (Mechanical Engineering)
Titanium alloy Grade 5 (Ti6Al4V) has attracted the interest of the engineering
community, because of its excellent physical and mechanical properties. Due to its low
density, superior quality at high temperature and good corrosion resistance, Ti6Al4V
alloy is used in the aerospace industry. The alloy has also been applied in many areas,
such as sport, marine, the chemical industry, the automotive industry and the biomedical
field – due to its excellent corrosion resistance in a corrosive environment or medium.
Because of the poor wear-resistance properties exhibited by the alloy, five weight
percent of tungsten (W) was agglomerated with it, this percentage weight addition of
tungsten was optimised, in order to improve its surface properties in this research study.
The tungsten is selected due to its superior strength, creep resistance, and structural
stability at elevated temperatures.
Trial experiments were first conducted with the two powders, Ti6Al4V and W
(Ti6Al4V+W). The parameters with good laser deposition process were selected for the
preliminary studies. The relationships between the process parameters on the material
characterizations were thoroughly investigated. Design Expert 9 software was used to
validate the experimental results. In the design of the experiment, the Response Surface
Methodology (RSM) was used to determine the required process parameters standard
order and the leverage, as well as the response to the input factors. The model was
validated to establish the variations between the predicted value and the actual value.
The laser deposited Ti6Al4V+W specimens were characterized through the evolving
microstructures, dry sliding wear, corrosion, microhardness and x-Ray diffraction.