Al matrix composites with a high volume fraction of reinforcements were fabricated with a compact of Al-Ti-B4C powder mixtures by quick spontaneous infiltration(QSI) process in an aluminum melt. Given the exothermal n...Al matrix composites with a high volume fraction of reinforcements were fabricated with a compact of Al-Ti-B4C powder mixtures by quick spontaneous infiltration(QSI) process in an aluminum melt. Given the exothermal nature of the reaction between CuO and Al, a certain amount of CuO addition to the Al-Ti-B4C system dramatically increases the adiabatic temperature and thereby enables the complete combustion reaction in an aluminum melt(about 1,173 K). After the QSI process, the compact fabricated with CuO retains its original shape and the obtained composite exhibits sound microstructure containing reaction products of TiB2, Al3BC and B4C. The formation of such reinforcements when adding CuO contributes to enhancing the properties of the composites that show far superior hardness and elastic modulus of 3.03 GPa and 158.9 GPa, respectively, with lower coefficient of thermal expansion(9.44 ppm?K-1) compared to those with no CuO addition.展开更多
Thick and hard ceramic coatings were fabricated on A356 aluminum alloy by using plasma electrolytic oxidation(PEO) technique. The microstructure and phase composition of the PEO coatings were examined by using SEM and...Thick and hard ceramic coatings were fabricated on A356 aluminum alloy by using plasma electrolytic oxidation(PEO) technique. The microstructure and phase composition of the PEO coatings were examined by using SEM and XRD method. It is found that the PEO coatings are mainly composed of crystalline α-Al2O3 and mullite. The dry sliding wear test of PEO coatings were carried out on a ring-on-ring wear machine. Results shows that there is hardly no wear loss of polished PEO coatings while the wear rate of uncoated aluminum alloy is 4.3×10-5 mm3·(N·m)-1 at a speed of 0.52 m·s-1 and a load of 40 N.展开更多
基金supported by a grant from the Fundamental R&D Program for Core Technology of Materialsfunded by the Ministry of Knowledge Economy,Republic of Korea(No.10037308)
文摘Al matrix composites with a high volume fraction of reinforcements were fabricated with a compact of Al-Ti-B4C powder mixtures by quick spontaneous infiltration(QSI) process in an aluminum melt. Given the exothermal nature of the reaction between CuO and Al, a certain amount of CuO addition to the Al-Ti-B4C system dramatically increases the adiabatic temperature and thereby enables the complete combustion reaction in an aluminum melt(about 1,173 K). After the QSI process, the compact fabricated with CuO retains its original shape and the obtained composite exhibits sound microstructure containing reaction products of TiB2, Al3BC and B4C. The formation of such reinforcements when adding CuO contributes to enhancing the properties of the composites that show far superior hardness and elastic modulus of 3.03 GPa and 158.9 GPa, respectively, with lower coefficient of thermal expansion(9.44 ppm?K-1) compared to those with no CuO addition.
基金This work was financially supported by the Fund of Beijing Jiaotong University,and by the OpenFund of State Key Laboratory of Tribology of China(No.SKLT02-4).
文摘Thick and hard ceramic coatings were fabricated on A356 aluminum alloy by using plasma electrolytic oxidation(PEO) technique. The microstructure and phase composition of the PEO coatings were examined by using SEM and XRD method. It is found that the PEO coatings are mainly composed of crystalline α-Al2O3 and mullite. The dry sliding wear test of PEO coatings were carried out on a ring-on-ring wear machine. Results shows that there is hardly no wear loss of polished PEO coatings while the wear rate of uncoated aluminum alloy is 4.3×10-5 mm3·(N·m)-1 at a speed of 0.52 m·s-1 and a load of 40 N.
