At the same time, the turn-around ring of the hammer head is made of special composite material, with the qualities of wear-resisting, self - lubricating, non-maintaining, easy changing etc.
同时锤头回转圈采用特殊复合材料，具有耐磨、自润滑、免维护、易更换等特点。
2
Self-lubricating composite which possesses superior antifriction and wear resistance has been one of the central issues for advanced material research.
具有优良减摩耐磨性能的自润滑材料是材料研究的热点领域之一。
3
All the valve's internal self-lubricating bearings are sliding bearings, the whole material the use of carbon steel PTFE liner.