Abstract: In a valve, especially for a shut-off or regulating means, having of a plate-like valve body of a metal or nonmetallic material having at least one layer of hard substance applied to the valve body, the coating consists of an alloy of silicon and/or carbon, preferably of Si.sub.x C.sub.1-x (wherein -x has a value of 0 to 1), and is applied to the valve body by the method of plasma CVD or plasma polymerization, monomers (gases or gas mixtures which contain the atoms which are to form the hard coating) are used, which contain carbon or carbon and silicon.

Abstract: On a machine element of a metallic material, for example, a piston or a piston rod (7, 7') for a shock absorber for a motor vehicle, with at least one hard-material coating deposited on the machine element, the hard-material coating essentially consists of an alloy of silicon and carbon, preferably of Si.sub.x C.sub.1-x, x having a value of from 0 to 1. The deposition of the hard-material coating occurs on the cathode or the anode of a plasma CVD unit at a pressure of the gas or gas mixture in the deposition chamber (1) of between 10.sup.-4 and 20 millibars.

Abstract: A method and apparatus for monitoring layer erosion in a dry-etching process. The apparatus has a first electrode that is electrically connected to a substrate to be etched, as well as a second electrode that is located above the first electrode. Both electrodes are situated inside a process chamber. An optical photometer is positioned outside of the process chamber and directed onto the substrate in the process chamber. Signals received from the optical photometer are amplified by an electrical circuit and are edited and displayed with a Fourier transformation. The etching process can be automatically interrupted when received periodic signals having essentially constant amplitude and frequency undergo a significant change during the etching process of the upper layer. That is, they are received as signals signficantly deviating from one another, this being identified by the electrical circuit as the passage from one layer to another layer of the substrate during the dry-etching process.

Abstract: A method for producing a transparent protective coating on a plastic optical substrate surface is disclosed. In particular, a substrate is positioned between two electrodes on the cathode in a reaction chamber. Once positioned, a noble gas is introduced into the chamber and the surface of the plastic optical substrate is bombarded. A monomeric organic compound of either siloxane or silazane is introduced into the reaction chamber and a bias voltage of a value in the range of 80 to 500 volts is obtained to polymerize the compound on the substrate surface. Following the beginning of this polymerization, oxygen is introduced into the reaction chamber in an amount of about 5 times the amount of the monomeric organic compound to form a mixture with the compound.