International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This part is a continuation of Part-1, which was studying the effect of anti-corrosion nano-materials coating using zinc (Zn) and cobalt (Co) on corrosion resistance and its relationship with mechanical properties. While, part 2 was on studying the linear stresses resistance after coating by using the same nanomaterials of paret-1 of carbon steel pipe and their relationship with chemical corrosion resistance using finite element analysis (FEA). The coating was tested with different thicknesses of nano-layers (300 μm, 600 μm, 900 μm, 10 μm) on a thick-walled cylindrical pipe subjected to a uniformly distributed internal pressure of 4 bars. The results showed that the value of linear normal stresses did not change when coating with 300 μm for both nano-coating materials. However, it was started to decrease slightly when covered with 600 μm of cobalt and continues to decrease with increasing the coating thickness. In addition, the results have shown that the overall improvement in linearized normal stresses and corrosion resistance due to cobalt coating can be about (66 %) higher in comparison with Zinc at 10 μm thickness of coating.

The paper presents the results of the research aimed at determining the quality of coatings applied by the HVOF spray coating technology and the advances in its application. WC-Co-Cr 86/10/4 nano covers were evaluated at two grain sizes. The effect of nano particle size on coatings quality was evaluated under abrasive wear conditions with bound abrasive in the initial state and after thermal cyclic loading. Coating thickness measurements, microhardness and structural analysis of the coatings were performed. As the number of thermal cycles increased, the hardness of the coatings increased. A thermal load between 600 and 800 ° C results in the crystallization of the amorphous phase, which leads to the precipitation of the WC phase from the Co-Cr matrix, and thus to an increase in the microhardness of the coating. The REM analysis of the structure of nano coatings confirmed that the exposure of the samples to the thermal load had an influence on their structural  composition. As the number of thermal cycles increased, the wear of the coatings under dry friction conditions increased.