Comparative study of the main properties associated with thin layers of coatings with the cobalt-chromium-tungsten alloy (stellite) and hard chromium plating used as reinforcements for wood sawing

摘要

The objective of this work is to study the possibilities offered by hard chrome plating (HC) as reinforcing coatings of the bandsaws in the sawmill industry, compared to Stellite coatings and wood energetics groups. Therefore, the properties associated with thin layers of the cobalt-chromium-tungsten alloy (Stellite) and HC are studied. The elemental chemical composition and the microstructure are determined by dispersed energy spectrometry and metallographic analysis, respectively. The mechanical properties like microhardness (Hv), the modulus of elasticity (E), and tribological performance are evaluated utilizing Vickers and Knoop microindentations and pin on-disk tests. The microhardness of the HC coatings is 24% higher, but its modulus of elasticity is 21% lower compared to the Stellite coatings, finding highly significant statistical differences. The HC has a Higher Coefficient of Friction (COF) and a higher specific wear rate than the Stellite coatings. The results concerning the values of the energetics groups of the woods demonstrate that the hardness of Group VI (higher hardness and density) represents only 1.3% and 1.7% of the microhardness of the Stellite and HC coatings respectively, and less than 1% compared to the modulus of elasticity of both coatings. This implies that there is a very low probability of incurring permanent deformation of the coatings due to the resistance to the wood to be penetrated. Based on the above, it is shown that hard chrome plating can be an interesting technique and application for the sawmill industry, especially for the longest bandsaws.