Hard-coat with Teflon

Jun 27,2022 | Views: 1421

Hard-coat with Teflon (MIL-A-63576A)

The main purposes of hard anodizing is to make the aluminum more resistant to corrosion. The PTFE(Polytetrafluoroethylene) coating is typically far thicker and harder than normal anodizing.

Types of PTEF coating: The anodic coating to be impregnated or coated shall meet the requirements of an unsealed Type III, class I coating as specified in MIL-A-8625.

--Type I coatings shall be the result of impregnating PTEF into the unsealed surface asperities of the anodic coating.

--Type II coating shall be the result of applying by dipping, spraying, or brushing a thermoplasting resin containing PTEF to the unsealed anodic surfaces. The resin is air cured.

--Type III coating shall be result of applying by spraying, dipping, or brushing a thermosetting resin containing PTEF to the unsealed anodic surface and then curing at 177° Celsius for one hour.

Thickness of PTEF coating: The thickness shall be as specified in the contract, order, or applicable drawing. The coating may vary in thickness from 0.0001 inch(0.1 mil) to more than 0.008 inch(8 mils). If a definite thickness is not specified in the contract, order, or applicable drawing, the nominal thickness of the coating shall be 0.002 inch(2 mils) for the anodic coating prior to impregnation with the lubricant. Unless otherwise specified, the thickness of the coating shall not vary by more than +/-10 percent.

Type I coating will normally add less than 0.0001 inch(0.1 mil) to the anodic thickness. If not otherwise specified, Type I coating thickness shall be 0.002+/-0.0002 inch(20+/-0.2mils) for the total anodic plus PTFE coating.

Type II and Type III coating can add from 0.0002(0.2mil) to 0.0007 inch(0.7mil) to the anodic coatings. Unless otherwise specified on the drawing or order, the Type II and Type III coating thickness shall be 0.0025+/-0.00025 inch(25+/-0.25 mils) for the total anodic plus PTFE coating.