Effect of Pre-Treatment on Substrates for Metal Coatings Fabricated by Low Pressure Cold Spray Technique

Abstract

Low pressure cold spraying is an attractive technique for onsite metal coating fabrication due to its compactness and portability. However; the bonding strength of the coating prepared by low pressure cold spraying is generally low; which restricts the further applications in engineering and industrial fields. To improve the bonding strength; pre-treatment on substrate surface can be an effective procedure. In this study; a low-temperature plasma treatment was applied to a pretreatment technique; and the effect of the treatment on particle bonding was compared with that of a laser treatment. Copper coatings on aluminum and copper substrates were selected and studied as basic metal materials. The SEM observation results show that the particle adhesion rate significantly increases by the laser and plasma treatments; due to the removal of the native oxide films on the substrates. The particle bonding on the plasma-treated substrate reveals better interfacial adhesion with less gap compared with the laser-treated one. The pre-treatment by low-temperature plasma can be an attractive technique to assist the cold spraying process due to the oxide removal ability and no thermal effect which can apply a wide range of materials.