Determination of the ideal hardness values for samples compounds and alloys fabricated from powder oxide of single metal elements
College Of Basic Education Research Journal,
2014, Volume 13, Issue 2, Pages 991-1012
AbstractIn this paper, the best values of the hardness of CuO and ZnO and their alloys have been determined. This is performed according to the chemical form of CuxZn1-xO for values 0, 0.2, 0.4, 0.6, 0.8, 1. Different pressure values (8, 10, 12.5, 15, 17) have been applied on the samples. After that, the hardness measurements have been performed with and without thermal coefficients according to the annealing and cooling. The annealing temperatures were 2, 3, 4 hr. Next, slowly cooling in the air (inside the oven) and fast cooling in the air are done, as well as, in water and oil.
The measurement results of the hardness of compressed and non-annealed CuO and ZnO under different pressures indicate these values were very small and approach to zero. This can be attributed to the lack of cohesion at room temperature.
Moreover the measurement results of the hardness of CuO have shown that the compressed samples under pressure (15-17 ton/cm2) and annealed with temperature 1000 Co have the highest values of the hardness, these samples have been annealed from 3 to 4 hr., then have been cooled slowly in the air and fast in the oil, their hardness values were 122 1nd 123, respectively. This depends on the method used in the study (Rockwell Hardness Test). With respect to the ZnO, the hardness values were different compared to the hardness values of CuO. The hardness value of CuO was 4, this depends on the(VickersHardness Test). The reason behind that may be attributed to the fragile, slack nature and smallness sizes of the grains.
The alloys with the chemical form CuxZn1-xO have been fabricated;studying of the pressure effects and thermal coefficients on the hardness values has been achieved depending on the method of (VickersHardness Test) because this method is more suitable for alloys. The hardness values of non-annealed alloys were very small because of the lack of cohesion of their grains; while the hardness of the annealed alloys which treated by slow and fast cooling have identical values approximately. Finally, it is observed that hardness reduces when mass percentage of ZnO/CuO is increased.
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