Novel nickel-free wear coatings for the container glass industry

As a material for tribological coatings of components that must exhibit very high wear resistance, nickel plays an important role. Nickel is considered a strategically important and, due to its high procurement risk, simultaneously a critical raw material.

Against this background, a publicly funded project by Neue Materialien Bayreuth GmbH focused on developing alternatives to nickel-based wear protection coatings. The application case was molds for the production of container glasses. Here, in addition to the parameter of wear resistance, high demands are also placed on the adhesion of the liquid glass. At the same time, the coatings should be more efficient and economical.

The focus of the project was on developing an aluminum-containing Al-Fe(X) coating material to avoid critical and cost-intensive materials. The coating was intended to combine high thermal conductivity with excellent wear and corrosion resistance while significantly reducing the adhesion of the glass to the mold.

Another focus was the development of an optimal process for a homogeneous inner coating of the complex glass mold geometries. For this purpose, thermal spraying processes were developed and successfully validated using 3D demonstration components. A systematic investigation of the geometry-related effects on process windows, residual stresses, and deformations enabled the derivation of a robust and industry-compatible process strategy that is generally applicable to coatings.

The project results are impressive:

• The innovative coatings are characterized by high hardness and coating density as well as excellent layer adhesion. No cracking was observed. 
• A significant reduction in glass adhesion was achieved, which improves the quality of the produced glass containers and reduces glass consumption.
• The coatings enable a significant extension of the lifespan of the molds under operating conditions.
• The manufacturing process can do without oil-graphite separating agents.
   

The work was carried out under the project coordination of Neue Materialien Bayreuth GmbH, a non-university research institution, with the project partners Wiegand-Glashüttenwerke GmbH, Chair of Metallic Materials at the University of Bayreuth, and Rauschert Heinersdorf-Pressig GmbH.

The project "Thermal Spraying of Aluminum-Containing Wear Protection Layers on Glass Molds for Environmentally Friendly Production of Container Glasses - Al-G" was funded by the Bavarian Transformation and Research Foundation (Funding Code: AZ-1477-20).