EFFECT OF PRESSURE RELIEF HOLE DEPTH ON EXPLOSIVE CONSOLIDATION OF ALUMINUM POWDER

Aluminum materials with high mechanical properties were prepared by explosive consolidation, and the mechanical properties, phase and microstructure of aluminum materials were characterized and analyzed. In three groups of tests with different depths of relief hole of 10 mm, 13 mm and 16 mm, the hardness of the aluminum block is similar, which is within the range of HV146.88~HV155.14. When the relief hole is 13 mm deep, the hardness standard deviation of aluminum block is the smallest, which is HV6.89, i.e., about 50% of the other two groups. The compressive strength and elastic modulus of the aluminum block prepared with 13mm pressure relief hole depth are the largest, which are 146.1 MPa and 6.85 GPa respectively. Similarly, the density of aluminum block made under the condition of 13 mm pressure relief hole depth is the largest, which can reach 98.31% of the theoretical density of pure aluminum, with the smallest standard deviation among the three groups of tests, which is 0.39%. It was found by metallographic microscopic test that there were long cracks on the surface of the samples prepared under the conditions of h=10 mm and h=16 mm. The reason was that when the gas storage in the pressure relief hole was small, the gas would exist in the aluminum rod sample; while when the gas storage in the pressure relief hole was large, the aluminum powder at the bottom would be pushed into the pressure relief hole, causing partial looseness. Both will lead to the decrease of the mechanical properties of the aluminum rod. Finally, combined with the fuzzy mathematics comprehensive evaluation method and analytic hierarchy process, the fuzzy mathematics evaluation model of the influence factors of the block aluminum explosive sintering is constructed, and the mechanical properties of the aluminum block prepared with different pressure relief hole depths are quantitatively optimized. The results show that, the comprehensive scores of aluminum prepared by explosive sintering are 73.18, 81.72 and 76.98 respectively, which demonstrate that a pressure relief hole depth of 13 mm will lead to the best mechanical properties of bulk aluminum.