| 摘要 |
<p>A rolling cone cutter has a bearing pin 15 on which is mounted a cone 17. A bearing sleeve 21 rotates with the cone and a rigid ring 23 is biassed against the sleeve by an energizing ring 29. There is an excluder ring 31. One or both the inter-engaging faces of the sleeve and the ring 23 is coated with a layer of DLC material. The DLC material, or diamond-like carbon, is a form of meta-stable amorphous carbon or hydrocarbon compound with properties very similar to those of diamond. To form the layer on the face 27 of the ring 23, a first operation comprises the deposition of material trom an RF plasma, sustained in hydrocarbon gases, onto negatively biased ring 23. After heating, face 27 is etched by argon ion bombardment. Then one or more metallic interlayers is applied from a sputter source such as a chromium target. Lastly, acetylene is introduced and a plasma is ignited between face 27 and the chamber walls. The acetylene decomposes to form carbon atoms that coat face 27 on the metallic interlayer with DLC. During the entire coating process, the temperature will be maintained below the lowest transformation temperature of the ring 23. Other processes are suitable, including primary ion beam deposition of carbon items. The coating preferably has a thickness of 2 to 3 micrometers, the hardness is in the range from 2,000 to 5,000 Knoop.</p> |
