Taiho Kogyo Co., Ltd.

The relatively uniform bismuth-copper film was electrodeposited between -15 and -20 mV in the sulfate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.Only copper was electrodeposited at -5 mV.The dendritic bismuth-copper film was electrodeposited under -20 mV.The cathodic current became constant between -20 and -400 mV, Therefore, bismuth-copper electrodeposition changes from charge transfer controlling to diffusion controlling at -20 mV.On the other hand, the uniform bismuth-copper film was electrodeposited between -5 and -35 mV in the methanesulfonate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.The dendritic bismuth-copper film was electrodeposited under -35 mV.The potential region for good electrodeposition in methanesulfonate electrolyte is wider than that in sulfate electrolyte.It is easy to control electrodeposition conditions by using methanesulfonate electrolyte.

In today's market, small-sized diesel engines used for passenger cars, RVs and com. use vehicles are being pushed to new limits in fuel consumption, output and durability.As a result of these demands, engine bearings are used under increasingly severe loads and temperaturesA problem with the conventional aluminum alloy bearings which are used in these conditions is their low fatigue resistance.For this reason, a new aluminum alloy bearing, which contains no lead and reaches new levels in fatigue and corrosion resistance, was developed by improving the tensile strength of the alloy to 185 MPa.The performance of this new bearing alloy is described.

Recent diesel engines require higher performance and longer life.Due to high cylinder pressure, the operating unit load and temperature of piston pin bushings become high.Therefore, good load carrying capacity, wear resistance and corrosion resistance are required for piston pin bushings.For this reason, we have studied the effect of additives (AlN, and Fe₃P) to copper alloy for corrosion resistance and the effects of hard particles added into the copper matrix for wear resistance and the machinability of materials.Based on the exptl. results, we have developed a new bushing material which improves the wear resistance and the corrosion resistance.