Effects of Electromagnetic Field and Lubricate Condition on the Surface Quality of Aluminum Alloy Billet during LFEC Processing

The microstructures of the aluminum billets could be improved markedly by low-frequency electro-magnetic casting (LFEC) processing. In fact, the low-frequency electromagnetic field (LFEF) also has favorite effect on the surface quality of billet. However, few public reports on the surface quality of LFEC aluminum billets could be found. Therefore, a new crystallizer together with a kind of lubricant was designed aiming at lowing surface turning quantity, and the effects of casting velocity, electromagnetic condition and lubrication on the surface quality of aluminum billets were investigated. The results indicate that LFEF together with the lubricate condition would be responsible for the surface quality of the billets, and the high surface quality billets could be achieved by optimizing the casting conditions.

Microstructure and Tribological Properties of a Ni-Base Laser Cladding on Aluminum Bronze

In the paper, a Ni-base composite cladding was cladded on the surface of QAl9-4 aluminum bronze by laser cladding technology, as well as its microstructure and tribological properties are studied. The results show that the microstructure of laser cladding is affected by solidification rate, and its wear behavior mainly lies on microstructure and lubrication condition. The microstructure of laser cladding is made up of cellular crystal and dendrite crystal. The microstructure of the surface cladding is cellular crystal, the middle section is crassitude dendrite crystal, and the bottom is coarse dendrite crystal and cellular crystal. Under dry friction condition, wear mechanism is abrasive wear and shedding strengthen phase, which has higher volume’s wear rate. Under lubricate condition, wear mechanism is abrasive wear and adhere wear, which has lower volume’s wear rate than that of dry friction. The average friction coefficient of the cladding under dry and lubricate condition are 0.39 and 0.15, the volume’s wear rate are 7.88×10-8mm3/N.mm and 1.56×10-9mm3/ N.mm, respectively. Therefore, the cladding has favorable wear resistance property under lubricate condition，and can be used as an excellent wearable material.