Olawale S. Fatoba

Effect of process parameters on the microstructure, hardness and wear resistance properties of Zn-Sn-Ti coatings on AISI 1015 steel: laser alloying technique

The deterioration of materials during industrial application poses a serious threat to the materials structural integrity. A materials susceptibility to wear and surface damage can be reduced by alteration of its surface chemistry, morphology and crystal structure which plays an important role in optimising a materials performance for a given application. The aim of the research was to investigate the enhancement in the microstructure and wear property of Zn-Sn-Ti ternary coatings on AISI 1015 steel by laser alloying technique using Ytterbium laser system (YLS). A laser power of 750-900 W, scanning speeds of 0.6 and 0.8 m/min, and alloy compositions of 25Zn-25Sn-50Ti and 20Zn-20Sn-60Ti were used in this study. At optimum composition of 20Zn-20Sn-60Ti and speed of 0.8 m/min, there was enhancement of 24% in wear resistance performance which was attributed to metastable intermetallic phases. The coatings were free of cracks with homogeneous and refined microstructures and good adhesion to the substrate. The response surface model (RSM) used authenticates reasonably with the experimental results.

The Effects of Sn Addition on the Microstructure and Surface Properties of Laser Deposited Al-Si-Sn Coatings on ASTM A29 Steel

Aluminium and its alloys have been successful metal materials used for many applications like commodity roles, automotive and vital structural components in aircrafts. A substantial portion of Al-Fe-Si alloy is also used for manufacturing the packaging foils and sheets for common heat exchanger applications. The present research was aimed at studying the morphology and surface analyses of laser deposited Al-Sn-Si coatings on ASTM A29 steel. These Fe-intermetallic compounds influence the material properties during rapid cooling by laser alloying technique and play a crucial role for the material quality. Thus, it is of considerable technological interest to control the morphology and distribution of these phases in order to eliminate the negative effects on microstructure. A 3 kW continuous wave ytterbium laser system (YLS) attached to a KUKA robot which controls the movement of the alloying process was utilized for the fabrication of the coatings at optimum laser parameters. The fabricated coatings were investigated for its hardness and wear resistance performance. The field emission scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS) was used to study the morphology of the fabricated coatings and X-ray diffractometer (XRD) for the identification of the phases present in the coatings. The coatings were free of cracks and pores with homogeneous and refined microstructures. The enhanced hardness and wear resistance performance were attributed to metastable intermetallic compounds formed.