{
  "$type": "site.standard.document",
  "coverImage": {
    "$type": "blob",
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  "description": "A piston ring which is provided with a carbon-based coating which has a low friction property and wear resistance, that is, a piston ring which has a carbon-based coating formed over its sliding surface, in which piston ring, the coating is a multilayer coating comprised of two types of layers…",
  "path": "/patents/997634",
  "publishedAt": "2012-10-03T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "C23C14/0605",
    "TPR CO LTD [JP]"
  ],
  "textContent": "A piston ring which is provided with a carbon-based coating which has a low friction property and wear resistance, that is, a piston ring which has a carbon-based coating formed over its sliding surface, in which piston ring, the coating is a multilayer coating comprised of two types of layers having different hardnesses laminated in at least two layers, a hardness difference between the two types of layers is 500 to 1700HV, a high hardness layer has the same or greater thickness than a low hardness layer, and the coating as a whole has a thickness of 5.0 µm or more. The high hardness layer has a thickness of 5 to 90 nm. The surface on which the coating is formed has a base material roughness of 1.0 µmRz or less.",
  "title": "Piston ring"
}