The number one problem for any product will be that eventually it will decay. Whether it would be because of the climate, natural surroundings or due to interaction between materials. A protective coating can be placed on the surface, which will delay natural causes taking its toll on the surface.
Plasma treatment can help save and expand the life of a material by applying uniform layers on to a surface to impede the diffusion of gases and to delay the interactions between solids and liquids. Also, barrier layers are used to prevent interdiffusion problems.