DLC coatings as interface

Question

DLC coatings as interface

Dougt115 (Mechanical)

(OP)

30 Oct 14 15:37

Does anyone have experience using DLC coating as a slip interface for 17-4 and titanium? The bushings in the current design are extruding under the loads and I cannot increase the dimensions. How well would this type of design wear over life?

.3125 diameter shaft by .25 wall with a 3200lb alternating load in a direction perpendicular to the axis of the shaft. 40 degree rotation. Need 2M cycles without servicing.

tbuelna (Aerospace) · Answer 1 · 2014-10-31 23:44:34

DLC is just a very hard thin surface coating. If the material substrate supporting the coating does not have adequate compressive strength to handle the loads/stresses without yielding then the coating will not be of any help. Since you noted that your existing bushing material is "extruding under the loads", then I doubt a DLC coating will help. Instead the hard, thin DLC coating would simply fracture and spall when the substrate material supporting it yields under load.

Dougt115 (Mechanical) · Answer 2 · 2014-11-03 12:07:08

The substrate material of the bushings is bronze. The material I am using is 17-4PH H900 to titanium. Under 3x loading I have had no loss of DLC coating to date.

The problem I am looking for expertise on is the life. I have 200K cycles on it so far and need to get to 2M minimum. I have not seen any documentation to say it will or will not make it.

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DLC coatings as interface