March 29, 2024

Which Ceramic Materials Can Aid in Protection Against Molten Zinc?

In the hot galvanizing industry, equipment such as tanks and tools are exposed to harsh conditions, particularly when in contact with molten zinc at temperatures ranging from 450 to 500°C. This exposure necessitates robust protection against dross adhesion and erosion, challenges that can significantly impact the efficiency, lifespan, and safety of the galvanizing process.

Some of the challenges posed by molten zinc include:

  1. Dross Adhesion: Dross is a by-product formed from impurities in the zinc bath, including oxides and other metals. Adhesion of dross to tanks and tools not only affects the quality of the galvanized product by introducing defects but also necessitates frequent cleaning, thereby reducing operational efficiency.
  2. Erosion and Corrosion: Continuous exposure to molten zinc can lead to erosion and corrosion of the equipment. This degradation is accelerated by the high-temperature and chemically reactive environment, posing risks of leaks or structural failures over time.

Certain thermal spray materials have emerged as particularly influential among the various materials employed for this purpose. This blog post explores the role of thermal spray materials, such as magnesium aluminum oxide (MgAl2O4) spinel, in providing protection against molten zinc.

The Significance of Thermal Spray Coatings

Technical ceramic materials are renowned for their exceptional properties, including high hardness, chemical inertness, and thermal stability, making them ideal candidates for protective coatings in harsh operating conditions. In the context of protection against molten zinc, ceramics offer a barrier that can withstand the corrosive and erosive effects of the metal at high temperatures.

A standout among ceramic coatings for this application is SPINEL Flexicord, a magnesium aluminum oxide designed for deposition via the MASTER JET® flame spray system. It is suitable for extreme temperatures (>1400°C) and offers excellent corrosion resistance, even in direct contact with molten metals like zinc.

Application through Thermal Spraying

Applying Spinel coatings via the MASTER JET® is a highly beneficial method of protecting a workpiece used in hot galvanizing assemblies. Spinel's low wettability means zinc does not stick to the coating, making the system easy to clean. Its resistance to abrasion likewise enables ease of cleaning with tools that might otherwise scratch the substrate. These coatings are also easy to apply to complex shapes using the MASTER JET® thermal spray gun. The gun offers high efficiency manual spraying, with extremely accurate material feeding ensuring high degrees of accuracy and reproducibility. Furthermore, this represents a one-step process, meaning there is no need to cure or sinter the ceramic coating after deposition.

Interested in Ceramic Coatings?

Deploying ceramic coatings like Spinel through thermal spraying techniques presents a robust solution to protecting components against molten zinc's corrosive effects. Spinel’s unique combination of high-temperature stability and ease-of-deposition via the MASTER JET® system makes it an economical approach to protecting key components in hot galvanizing systems. These coatings can effectively prevent corrosion, dross adhesion, and erosion, while providing added functionality throughout the process.

Our coatings expertise spans many ceramic materials and can be applied to various metallurgical applications. We have a track record of co-developing solutions for various molten metals. If you would like to learn more, including to request samples, contact a member of the Saint-Gobain team today.