Porosity effect on the tribological properties of Al-Si alloys for diamond-like carbon coating of cold sprayed

Abstract In this study, diamond-like carbon (DLC) coating made from spherical powder SP and Irregular powder IP manufactured for plasma of cold sprayed by gas atomization is presented. Sliding assessment is carried out at different loads on each DLC coating. All DLC coating surfaces are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Furthermore, coatings show low porosity and extreme hardness. Irregular powder IP coatings have proved to be less hardness than SP coatings. In case of IP coatings, abrasive plowing with used particles is resulted in an increased wear, while the available porosity in SP of the used particles is formed in some points of reduced sliding of wear. Coatings of IP cause an increasing of coefficient of friction (CoF). The load limitations are associated with tribooxidation in IP coatings, while mixed particles together with tribooxidation result in lower CoF with SP coatings. The range of CoF for all test parameters is 0.24–0.32. Transmission electron microscopy (TEM) shows characteristics body-filled pores composed of a deformed material with an ultrafine microstructure and micron-sized particles. The characterization confirms that 30% of pore-filled coatings are ultra-deformed fabric with microstructure and particles, while the worn surfaces have a rough microstructure. The effects confirm that SP hardness and porosity help attract particles and reduce abrasiveness.