Published 10/1/2006

Ion Beam Enhanced Deposition Process Provides Wear- and Corrosion-Resistant Coatings For Mold Surfaces

Coating Specifics

According to Arnold H. Deutchman, Ph.D., Chairman and Director of R&D for Beamalloy, IBED processing combines the benefits of thermal diffusion processing and conventional coating technologies because the coating atoms first penetrate into the substrate to form a case layer in the surface, and then are grown out from this case layer as a thick coating.

IBED is a physical, non-equilibrium coating process implemented by the simultaneous bombardment of a growing film with an independently controllable beam of energetic atomic particles (see Figure 1). “The growing film is generated either by vacuum evaporation or ion beam sputtering,” Deutchman notes. “The independent beam of particles consists primarily of charged atoms (ions) extracted at high energy from a broad beam ion source. Because control of the ion beam is independent of the coating vapor flux, the energy of the ions in the beam can be varied over a wide range and chosen within a very narrow window. This allows a high degree of control over coating nanostructure and optimization of coating properties such as interfacial adhesion, density, grain size/morphology and internal stresses. Essentially a line of sight process, sources of the reactant fluxes are located so that they simultaneously illuminate the components to be coated. The components are mounted to an angling, rotating platen assembly that is used to uniformly expose all surfaces of the components to both reactant fluxes.”

Advantages

The following characteristics of the IBED process make it an ideal method for the coating of injection and extrusion mold tooling:

Low Temperature: Since IBED is a physical—not a chemical or thermal process—coating adhesion and growth is achieved without the external application of heat and processing temperatures can be held below 200°F (93°C) if desired. Thus, there is no danger of dimensional distortion or tempering of precision mold tooling during coating.
A Variety of Substrates Can Be Coated: Since IBED coatings are ballistically bonded to the substrate, there is no practical limit to the types of alloys that can be coated. A full range of mold steels and tool steels (P20, H13, S7, D2, A2, M4, and CPM10V) and stainless steels (316, 440C) can be coated. Alloys of non-ferrous materials, such as nickel, aluminum and copper also can be coated for use under certain conditions. This allows flexibility in mold tool material specification when trying to optimize both wear resistance and thermal conductivity.
A Variety of Coatings Can Be Deposited: Metallic coatings including Cr and Ni and hardcoatings, including TiN and Cr2N, are routinely deposited on mold tooling using the IBED process at thicknesses in the range of 1 to 5 microns (40 to 200 μ-in.) (1 μmeter = 10-6 meter and 1 micron = 1 μmeter).
No Regrinding or Repolishing Required: IBED coatings replicate the original surface on which they are deposited—regardless of whether the surface is highly polished or textured. Thus, there is no need for post-coating regrinding, repolishing or retexturing.
Highly Repeatable Properties: Since the nanostructure of IBED coatings is highly uniform, the coatings are free of voids and pinholes, they exhibit improved adhesion and cohesion, and the mechanical properties of IBED-deposited coatings are better than the equivalent coatings deposited by plating or PVD. And the coating properties are highly repeatable—a must for volume production of precision mold tooling.

For improving the performance and productivity of your precision mold tooling, IBED technology is worth investigating.