Surfaces, articles, and processes having silicon-nitride-containing thermal chemical vapor deposition coating are disclosed. A process includes producing a silicon-nitride-containing thermal chemical vapor deposition coating on a surface within a chamber. Flow into and from the chamber is restricted or halted during the producing of the silicon-nitride-containing thermal chemical vapor deposition coating on the surface. A surface includes a silicon-nitride-containing thermal chemical vapor deposition coating. The surface has at least a concealed portion that is obstructed from view. An article includes a silicon-nitride-containing thermal chemical vapor deposition coating on a surface within a chamber. The surface has at least a concealed portion that is obstructed from view.