论文部分内容阅读
铜-石墨电刷在电动机和发电机中传导电流。铜用来提高电刷的电导性和强度。通常,低压应用要求电刷具有较高的电导性,这可以通过增加电刷中铜的百分比来实现。但是,增加铜的含量,却会降低石墨的自润滑作用,从而缩短电刷的使用寿命。 传统上,一直使用电解铜粉来生产含有高石墨的碳刷。电刷需要高压坯强度和低电阻率,具有高比表面积和不规则枝晶结构的电解铜粉能够提供这些特性,因此电刷制造厂商在大多数情况下都选用电解铜粉。 1980年,美国最后一家电解铜粉制造厂因环保和经济问题而停产。由于电解铜粉在轴承、电刷和金属摩擦材料等传统产品应用方面不断失去市场,因此其粉末生产厂的经济规模萎缩,生产成本增加,经济活力几乎荡然无存。随着世界各地日益强调环保问题,电解铜粉生产业由于产生废酸,其生存受到严重威胁。 为了解决这些问题,SCM公司研制成功一种无环境污染的非电解工艺藉以生产各种钢粉。这些铜粉具有高比表面积和极不规则的粒状,可给压制成型式电刷带来极佳的压坯强度,而且产生的电导性能与铜-石墨电刷产品使用的电解铜粉相同。下文将这些铜粉的性能与市面上出售的两种电解铜粉进行比较。
Copper-graphite brushes conduct current in motors and generators. Copper is used to increase the conductivity and strength of brushes. In general, low voltage applications require brushes with higher electrical conductivity, which can be achieved by increasing the percentage of copper in the brushes. However, increasing the copper content, but will reduce the self-lubricating graphite, thereby shortening the life of the brush. Traditionally, electrolytic copper powder has been used to produce carbon brushes containing high graphite. Brushes require high green strength and low resistivity. Electrolytic copper powders with high specific surface area and irregular dendrite structure can provide these characteristics. Therefore, brush manufacturers choose electrolytic copper powder in most cases. In 1980, the last electrolytic copper powder factory in the United States was discontinued due to environmental and economic problems. As electrolytic copper powder continues to lose market in applications of traditional products such as bearings, brushes and metal friction materials, the economic scale of its powder manufacturing plant has shrunk, production costs have increased, and economic viability has almost vanished. With the increasing emphasis on environmental protection in various parts of the world, the survival of electrolytic copper powder production industry is seriously threatened due to the generation of waste acid. In order to solve these problems, SCM successfully developed a non-electrolytic pollution-free process to produce various kinds of steel powder. These copper powders, with their high specific surface area and extremely irregular grain shape, provide excellent compact strength for press-formed brushes and produce the same conductivity as electrolytic copper powder used in copper-graphite brushes. The performance of these copper powders is compared with two types of electrolytic copper powders on the market.