Open AccessWhen designing any spacecraft, the opening elements of the structure are applied in which deployment and locking units are used.
There is a transporting step i.e. an insertion of the deployment unit in the folded state into orbit. During this step the deployment unit is under considerable vibratory loads, which are accepted by thrusts. Since the thrusts at this step work under increased wear conditions it is offered, considering a protuberant surface hardness of the micro-arc oxide (MAO) coating, to replace a constructional material of the thrusts with a larger density for the MAO-coated aluminium alloy.
The step of deploying, at which required angle of deployment is provided by the rolling unit, is realized after the spacecraft has been placed into calculated orbit. This unit contains the target sleeve with the bearing, which provides reliable locking by means of the penetration in the inner cone of beam sector. To increase the product reliability and avoid a possibility for occurring the wear slot and burrs it is necessary to increase the hardness of the sector surface on which the target sleeve bearing rolls. The most rational solution is to form the local micro-arc oxide coating on the beam sector surface.
Application of the micro-arc oxidation of aluminium alloys and research of the micro-arc oxidation specificities enable us:
1) to decrease the typical deployment unit mass (by 0.221 kg or 0.85 %);
2) to increase the rolling unit operation reliability;
3) to design the schemes and select the conditions to form the micro-arc oxide coating on the parts of the typical deployment unit.
The micro-arc oxide coating formed on the aluminium alloy is of significance for the aerospace industry that uses a diversity of aluminium alloys and prefers the structure mass decrease as much as possible. It should be appreciated that the process to form the micro-arc oxide coating is production friendly because it does not need the complex expensive equipment and is easily regulated by changing the electrolyte composition and the current conditions.