The heat treatment of TripleHard chromium is necessary, as it strengthens the coating and the adhesion of the coating to the base material. Heat treatment changes the microstructure of the coating and gives it its final properties. Without the treatment the coating has poor mechanical properties and comes of easily.
Oven / Induction
This depends on the base material. The best situation would be that the base material is in soft state before plating. This way there is no danger of unintentionally softening the material during heat treatment. For many materials, the hardening of the base can be done simultaneously with the TripleHard hardening process. This saves process steps at every stage of the material processing.
Corrosion resistance of TripleHard chromium is good. At the table below, you can find the approximate NSS test hours that different TripleHard coating will resist corrosion.
TripleHard process is innovative and has been under continuous development for years. Trivalent chromium combined with the TripleHard additive and patented process lead to a microfissured, dense structure with excellent adhesion and strong mechanical properties. The network of microcracks strengthen the structure and enable good corrosion resistance as the cracks do not reach the base material. The microcracks are also a place for lubricants enabling low friction. The high hardness provides good wear resistance and also low friction even without a lubrication.
Base materials must be metallic and conductive. Because the heat treatment process requires temperature above 500 °C, this excludes some materials with low melting points like Aluminum and Copper. We are constantly developing our Technology to include as many materials as possible. Some materials might require a thin Nickel underlayer for the plating to be successful.
TripleHard chromium can be used to replace traditional hexavalent chromium in many applications. Because of its superior properties, a thinner layer might also be enough to provide similar properties and protection for the base material. In some cases, TripleHard can also be a replacement for thermal spray coatings or another special coatings, which are usually more expensive and require heavier machining afterwards. TripleHard process can be tailored to suit customer needs in terms of layer thickness from a few micrometers to several hundred microns. The heat treatment for TripleHard can be designed so that base material hardening can be executed simultaneously saving time and money.
- Hydraulic cylinders
- Shock absorbers
- Engine parts
- Wear parts
- Gun barrels
- Pipes; inner and outer surfaces
Because of the excellent wear, corrosion and acid resistance, TripleHard is at its best at difficult and demanding environments such as mines, process industry and heavy equipment. All of this means longer lifetime of parts and lower maintenance requirements
- Air ventilation
- This is one of the biggest expenses with energy ja labor costs in hexavalent chromium process.
- Compared to hexavalent chromium process the requirements for air ventilation are much lower; a standard fume removing ventilation above the TripleHard bath is enough. Air purification system required with hexavalent chromium is not needed.
- Waste water
- Waste water treatment is much simpler than with hexavalent chromium. Trivalent chromium is not soluble to water and thus requires less steps during the water treatment. Also, the substances are much less hazardous than with hexavalent chromium.
- Costs is somewhat in a similar range with hexavalent hard chrome but remarkably lower comparing with thermal spraying. Steps are taken at Savroc to reduce the costs of chemicals. But, it is good to keep in mind that the chemical costs are only a minor part of the total costs in terms of the whole process. The cost of hexavalent hard chrome is predicted to increase due to tightening environmental and occupational safety requirements, while trivalent chrome price is gradually decreasing in function of growing production.
- No authorization fees
- Chromic acid requires a license for use and it will only get more expensive, if even granted, in the future due to the danger of the hexavalent plating process.
- TripleHard process involves only REACH-approved chemicals are require no permits or licenses!
- Air ventilation
The process is very similar to hexavalent plating process with a few changes. Pretreatment includes the following process steps (between each step is rinsing with deionized water):
- Removal of oil, grease and other impurities from the surface of the piece.
- An acidic bath to activate the surface of the piece and to remove any corrosion or other impurities.
- This step is optional
- Different type of Nickel baths can be applied or TripleHard can be plated directly onto the base material
- TripleHard chromium
- Trivalent chromium electrolyte with TripleHard additive
- Bath temperature is only about 35 °C
- Heat treatment
- Heat treatment can be executed with an oven or by induction coil
- Heat treatment temperature is between 500-700°C- Time required at 700°C is about 30 minutes, lower temperatures than this require longer heat treatment.
- Surface polishing can be done with a polishing wheel (e.g. cotton) together with a polishing wax.
The plating speed of TripleHard process is approximately 0,50 – 0,70 µm/min.
TripleHard coating thickness can be controlled with the plating time. Coating thickness can be from a few microns up several hundreds of micrometers. Usually a layer of 20 – 40 µm is sufficient.