Friction of In Situ Molybdenum Disulphide

The validity of the description of this patented procedure was also challenged on the grounds that molybdic oxide needs to be present in the plated film for the conversion to take place. It is interesting, therefore, that C E Vest introduced an important modification to the process in order to electrodeposit molybdenum trioxide instead of molybdenum metal when studying the application of the technique to the lubrication of spacecraft components. Vest s modification was to use a mixed plating bath of molybdenum trioxide in an alkali salt solution such as ammonium formate. The component being coated formed the cathode, and the molybdenum was probably present in the bath in the form of ammonium molybdate. 

A typical process would include some or all of the following stages - 

Electroplate with a metallic base film such as copper. 

Electrodeposit molybdenum trioxide from the mixed bath with a current density typicaily about 18-20 A/m, and deposition time about 3 to 10 mins., depending on the thickness required. 

Place the coated component in a pressure vessel, evacuate to 10 Torr and fill with hydrogen sulphide to 25 - 30 bars, raise the temperature to 195° 5°C and maintain for between 4 and 12 hours. 

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