Metal treatment – Stock – Copper base
Patent
1997-08-06
1999-08-17
Ip, Sikyin
Metal treatment
Stock
Copper base
148434, 148687, 420485, 420487, 428545, C22C 906, C23C 1800
Patent
active
059388641
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a copper-based sliding material, more particularly to the sliding material for such parts used under the lubrication of a lubricating oil which contains sulfur-based additives, such as a bush or washer of a transmission, a piston-pin bush, a cam bush, a balancer bearing (bush metal) or various parts of a turbo-charger, i.e., a floating bush, a thrust washer or the like. The present invention also relates to these parts.
BACKGROUND TECHNIQUE
Heretofore, lead bronze or phosphorus bronze has been used as the above-mentioned sliding materials. In addition, proposals have been made to enhance the seizure resistance of these copper alloys, such as by adding the matrix-strengthening elements, such as P, Al and the like, or adding Bi or the like which has good compatibility. These proposals have achieved some success.
However, when the lead bronze or phosphorus bronze is used in the lubricating oil having a high sulfur content and at a high temperature, black copper sulfide is formed on the surface. Since this copper-sulfide layer is of low-strength and is not tightly bonded to the substrate, such layer easily peels off from the substrate. It has consequently, turned out that seizure or abnormal wear thus occurs. Furthermore, it has also turned out that the copper alloys are corroded by the sulfur components of the lubricating oil, which leads to decrease in strength of the material and hence accelerates fatigue. In addition, the seizure of the lead bronze and the phosphorus bronze has been readily incurred under such sliding condition which brings about a mixture or boundary lubrication due to the small amount of lubricating oil.
Engine oil, transmission oil, gear oil or the like are the lubricating oil which lubricates between the above-mentioned sliding materials and the opposite material. The sulfur-based additives are added to these oils.
First, the additives to the gasoline-engine oil are dialkylmonosulfide for preventing the oxidative deterioration of the engine oil, a sufonate- or phenate- base metal detergent agent for cleaning the sludge formed by oxidation of the engine oil, dithiophosphate molybdenum compound or dithiocarbamate molybdenum compound for preventing foaming of the low-viscosity engine-oil, or the like. The above-mentioned dialkylmonosulfide is believed to ionically decompose the hydroperoxide which is formed by the oxidation of the base oil. However, detrimental effects of the additives are also pointed out. For example, the metal-based detergent agent forms sulfate-ash or sludge. The amount of its use is therefore limited. In addition, it is said that the foaming-preventing agent may exert a detrimental effect on the performance of the bearing metal.
ZnDTP (dialkyldithiozincphosphate) is added to the diesel-engine oil as a countermeasure against the wear due to soot. Into the rotary-engine oil, olefin sulfide, sulfurized oil or the like is added as the sulfur-based extreme pressure agent, and thiozinc-phosphate, dithiocarbamate molybdenum sulfide is added as the organic-metal anti-wear agent.
Into the transmission oil and the gear oil, olefin sulfide, sulfurized oil or the like is added as the sulfur-based extreme pressure agent, and thiozinc-phosphate or dithiocarbamate molybdenum sulfide is added as the organic-metal anti-wear agent, phosphate-esteramino-salt as the phosphorus-base anti-wear agent. The sulfur concentration ranges from 0.37 to 1.7% in the commercially available oil at present.
It is known that, when the above-mentioned various oils deteriorate, the oil incurs corrosion problems in the copper-based sliding materials. As a corrosion countermeasure, the present applicant filed the following patent applications.
U.S. Pat. No. 4,878,768: The deteriorated oil causes the corrosion of the Pb phase present in the clearances between the skeleton of the Cu--Pb based sintered alloy used as a sliding bearing of a diesel engine. In order to prevent such corrosion, In is added to the Pb phase.
Japanese Unexamined Patent Publication N
REFERENCES:
patent: 4308153 (1981-12-01), Mori
patent: 4641976 (1987-02-01), Kar
patent: 5091098 (1992-02-01), Tanaka et al.
Kamiya Soji
Kira Toshihiko
Tomikawa Takashi
Ip Sikyin
Taiho Kogyo Co. Ltd.
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