University of California

Other

Gm Global Technolgoy Operations, Inc.

Kevin C Walter

Michael A Nastasi

Joseph V Mantese

Don Mayo Coates

Gerard Wladyslaw Malaczynski

Alaa AbdelAzim Elmoursi

Michel G Tuszewski

Aboud H Hamdi

Deok-Hyung Lee

Xiao-Ming He

Donald J Rej

Xiaohong Qiu

Blake P Wood

Process for forming adherent coatings using plasma processing. Plasma Immersion Ion Processing (PIIP) is a process where energetic (hundreds of eV to many tens of keV) metallic and metalloid ions derived from high-vapor-pressure organometallic compounds in a plasma environment are employed to deposit coatings on suitable substrates, which coatings are subsequently relieved of stress using inert ion bombardment, also in a plasma environment, producing thereby strongly adherent coatings having chosen composition, thickness and density. Four processes are utilized: sputter-cleaning, ion implantation, material deposition, and coating stress relief. Targets are placed directly in a plasma and pulse biased to generate a non-line-of-sight deposition without the need for complex fixturing. If the bias is a relatively high negative potential (20 kV-100 kV) ion implantation will result. At lower voltages (50 V-10 kV), deposition occurs, and the extent of the surface modification can routinely be extended between 1 &mgr;m and 10 &mgr;m. By combining plasma based implantation and film deposition, coatings with greatly reduced stress are possible, allowing the ultimate coating thickness to be expanded to tens of microns.

Forming adherent coatings using plasma processing

A plasma-based method for the deposition of diamond-like carbon (DLC) coatings is described. The process uses a radio-frequency inductively coupled discharge to generate a plasma at relatively low gas pressures. The deposition process is environmentally friendly and scaleable to large areas, and components that have geometrically complicated surfaces can be processed. The method has been used to deposit adherent 100-400 nm thick DLC coatings on metals, glass, and polymers. These coatings are between three and four times harder than steel and are therefore scratch resistant, and transparent to visible light. Boron and silicon doping of the DLC coatings have produced coatings having improved optical properties and lower coating stress levels, but with slightly lower hardness.

Optically transparent, scratch-resistant, diamond-like carbon coatings

Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

Plasma treatment for producing electron emitters

A process for forming an adherent diamond-like carbon coating on a workpiece of suitable material such as an aluminum alloy is disclosed. The workpiece is successively immersed in different plasma atmospheres and subjected to short duration, high voltage, negative electrical potential pulses or constant negative electrical potentials or the like so as to clean the surface of oxygen atoms, implant carbon atoms into the surface of the alloy to form carbide compounds while codepositing a carbonaceous layer on the surface, bombard and remove the carbonaceous layer, and to thereafter deposit a generally amorphous hydrogen-containing carbon layer on the surface of the article.

Process for the formation of wear- and scuff-resistant carbon coatings

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Los Alamos, NM, United States of America

Kevin C Walter