Investigation of production with plasma spray method, characterization and wear behaviour of BN, B4C and SiC reinforced al coatings

In this study, aluminium matrix composite coatings with different reinforcement materials were sprayed on stainless steel substrates by using atmospheric plasma spraying method. Metco 52C-NS coded Al-12Si powder of Metco Sulzer company was used as matrix material and SiC, B4C and h-BN were used as reinforcement materials. Each reinforcement materials were added into matrix material 25%wt and 50%wt. Before coating process, mechanical alloying was proceeded to powder mixtures. Charecterization of these powder mixtures was made. Then coatings were sprayed. After the surface roughness, porosity and reinforcement rates of coatings were measured, coating thickness, microhardness, microstructure investigation, wear tests, SEM and XRD analysis were made.Two different conditions (dry sliding and distilled water) were used in wear tests. Tests were maintained with 2N, 5N and 10N loads and sliding distances of 50m, 100m, 150m and 200m for dry sliding and with 2N and 5N loads and sliding distances of 100m ve 200m for distilled water. Sliding speed was 10 cm/s. Ø6 mm alumina balls were used as counter material. Wear loss was calculated in terms of weight and volume. Stereo microscope photographs was taken from wear surfaces and contact points of counter material and SEM-EDX analysis was made.According to the results of the tests, it was observed that surface roughness had been decreasing by the increase at the rate of reinforcement in content of coating. In quantitative phase analysis made by using the surface of coatings, porosity had been increased by reinforcement rate. The rate of SiC reinforcement in the content of coating were less than the rate before coating process. That arised from the vaporization of SiC particles at the high temperatures. Differences were not encountered in B4C reinforced materials, as in SiC reinforced materials. In the micro hardness tests made by using cross section of coatings, hardness increased by the increasing rate of reinforcement. The highest hardness value was reached in the coatings with 50% B4C reinforced. The worst mechanic values was reached in the h-BN reinforced coatings, because BN used in the study had hexagonal structure.The best wear resistance was measured in wear tests which was in distilled water and especially with 50% B4C reinforced coatings. In distilled water condition, the results were better up to 10 times than in dry conditions. This was the result from forming Si(OH)4 colloidal gel between the counter material and coating in distilled water condition. This gel formation was proved by colorimetric analysis.