PVD Coatings Overview

While liquid nitriding is a surface modification technology, PVD coating involves the deposition of thin (2-10 microns; 0.0001"-0.0004") films on the surface of components. The PVD coating process, conducted under high vacuum conditions, can be divided into three stages:

  • Evaporation - Removal of material from the target, source or cathode.
  • Transportation - Travel of evaporated material from the source to the component to be coated.
  • Condensation - Nucleation and growth of the coating on the component surface.

Material is usually extracted from a high-purity solid source, such as Titanium, Chromium etc., by sputtering or by an arc-discharge. The transportation step is through a plasma medium. Plasma is a collection of charged particles, whose constituents can be influenced by magnetic fields and tend to travel in straight lines or "line of sight" from source to substrate. Different characteristics are imparted to the plasma depending upon the technique used to generate it. A PVD coating is formed when plasma constituents and reactive gases, such as nitrogen, combine on the component surface to form thin and very hard coatings such as Titanium and Chromium nitride.

Besides its specific chemical constituents and the architecture of the sub-layers, the properties of a PVD coating depend upon: ion energy; the degree of ionization of the metal ions, and mobility of the atoms condensing on the substrate surface. If a source material, such as a hydrocarbon gas, is used, a very hard, ultra low-friction Diamond-like-Carbon (DLC) coating can be deposited. This gas based process is referred to as PACVD - Plasma Assisted Chemical Vapor Deposition.

There is a broad range of available PVD technologies - including conventional arc deposition and magnetron sputtering, coupled with technology enhancements that yield high deposition rates and thin films with high adhesion and diverse microstructures. HEF PVD coatings are deposited using three different technologies:

PEMS: Plasma Enhanced Magnetron Sputtering

HEF patented PEMS is a magnetron sputtering process enhanced by an auxiliary plasma source. This triode system allows independent control of material flux, ion energy and substrate bias. PEMS can provide a multitude of high performance coatings with application customized hardness, density and toughness.

CAM: Coating Assisted by Microwaves

CAM permits the deposition of hard and ultra-low friction coatings at a very low temperature. Another major advantage is the ability to coat at low pressure, allowing more efficient use of the coating chamber and improved productivity.

M-ARC: Modified ARC

This high throughput plasma-arc method was developed by HEF's subsidiary, Northeast Coating Technologies (NCT), and dramatically reduces droplets normally associated with arc-deposited coatings. These coatings are a cost-effective solution for a wide range of carbon-free PVD coatings.