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Model Melonite -QPQ® Thermochemical Quench-Polish-Quench (DHQN)
IBC Coatings Technologies uses a thermochemical quench-polish-quench (QPQ® see registered trademarks disclaimer at the bottom of the page) nitriding process equivalent to Melonite® to harden, strengthen, and improve the corrosion resistance of metal components and equipment. Unlike some other finishes and treatments, Melonite® has a predictable and consistent outcome that significantly strengthens the surfaces of carbon steel, stainless steel, alloy steel, and austenitic steel products. It can also be highly effective when used for cast iron and sintered iron, as well. Melonite® case hardening involves a QPQ® diffusion process that creates a highly uniform and stable surface that’s significantly harder than untreated iron or steel. Thus, parts, components, and equipment treated with this form of nitrocarburizing (also called liquid nitriding) are far more resistant to normal wear and tear, even under the harshest conditions.
This process involves multiple steps, including molten salt baths, polishing, and rinsing, during which nitrogen, carbon, and oxygen are diffused into the surface of the metal, creating the case hardening effect that customers want for the parts they depend upon day in and day out.
Across industries, companies require components, parts, and equipment to perform to a certain standard, even under harsh, corrosive conditions with massive amounts of friction. Thanks to Melonite® (also called Tenifer® or Tufftride®), you can get the finest case hardening process to ensure the best performance for your products for years to come.
Melonite® processing produces a hardened, corrosion-resistant surface that will out-perform metal plating (hard chrome, zinc, or nickel), gas nitriding, Parkerizing®, and black oxide or bluing. While these traditional surface finishing processes were used in many industries for many years, they are each being methodically replaced by a superior finishing process – Melonite®.
The first step in the Melonite® process is to place the applicable parts or components in a preheat furnace. Once these parts are pre-heated to the appropriate temperature, they’ll be immersed in a molten, aerated solution of salts containing nitrogen and carbon. This step, which is referred to as nitriding, will generally last up to two hours, depending on the parts and the conditions they will be exposed to.
After nitriding, the parts are treated in an oxidation bath, usually for a period of up to 30 minutes, forming a surface layer of corrosion resistant magnetite (Fe3O4). The parts are then fully quenched and rinsed using a water bath.
The next phase of the process, polishing, is specifically designed to restore the part’s original surface finish. Polishing techniques and processes vary, but this step may be completed with centerless or vibratory polishing, lapping, glass bead blasting, or by another method of surface polishing.
Once the polishing is finished, the part will be immersed once more in an oxidizing salt bath, followed by a second water quench and rinse. This is why the process is referred to as quench-polish-quench, or QPQ®.
This unique process creates a much harder, more uniform surface condition that protects parts, components, and equipment from corrosion, friction, heat, and other wear and tear far better than coatings like nickel or chrome plating.
In addition to being harder and more wear resistant, when the QPQ® process is complete, the parts will have a smooth black finish that is clean and attractive with no need for painting or further finishing treatments.
Advantages of Melonite® Case Hardening:
Why choose Melonite® or Tufftride® case hardening over some other finish or coating?
Consider a few advantages that this process has over other alternatives:
- Improved wear and corrosion resistance
- Improved heat and friction resistance
- Increased fatigue strength
- An attractive black finish
Depending on the Melonite® process you choose for your parts, other advantages also include:
- Less friction between moving parts
- Smoother surfaces