A hard material layer having a relatively low frictional resistance, which can be produced by impregnating the layer with a lubricant. Zirconium oxynitride layer, which has zirconium-, nitrogen- and oxygen-containing phase, is used as a hard material layer. The presence of the phase in the zirconium oxynitride layer leads to a perceptible reduction of the layer frictional resistance, such that further processing steps can advantageously be saved on coating of substrates, such a impregnation. The coating (26) can, for example, be applied on a tool (27), which is appropriate for metal-cutting machining a work piece (28). With the low frictional resistance, a dry machining of the work piece (28) can be executed with the tool. Another application is the coating of highly stressed components of fuel injection valve.