STi System for Spraying Titanium
The Kermetico STi was developed as an answer to an industry request for a uniform non-oxidized Titanium coating with a thickness of 50 to 250 microns. (0.002”-0.010”).
This Titanium-focused system sprays non-oxidized dense Ti and Ti alloy coatings.
This system is designed for spraying of Ti alloy and titanium coatings in the air. The STi system allows repairing titanium alloy parts.
Titanium is not an easy material to spray. It reacts with oxygen and nitrogen at relatively low temperatures. That is why most of the developers were trying to deposit it with a vacuum or an inert gas atmosphere. These approaches make the coating extremely expensive.
Kermetico have chosen a different approach, creating an inert atmosphere inside the high velocity thermal spray gun.
Kermetico HVAF STi System Spraying a Titanium Coating
A keen observer will notice in the picture that the Titanium jet is several times narrower than the nozzle and starts oxidizing around 150 mm (6”) from the nozzle.
Key Features
- High-velocity thermal spray titanium coatings in the air in an inert gas shroud.
- Low level of oxidation, silver-like coating appearance.
- Dense coating.
- For corrosion resistant coatings and material build-up.
Sprayed Ti Alloy and Titanium Coatings Properties
- The two most useful properties of titanium are corrosion resistance and the highest strength-to-density ratio of any metallic element.
- In its unalloyed condition, titanium is as strong as some steels but less dense.
- Like aluminum and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air.
- Titanium readily reacts with oxygen at 1,200°C | 2,190°F in the air, and at 610°C ] 1,130°F in pure oxygen, forming titanium dioxide.
- It is slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation.
- When it first forms, this protective layer is only 1–2 nm thick but continues to grow slowly; reaching a thickness of 25 nm in four years.
- Atmospheric passivation gives titanium excellent resistance to corrosion, almost equivalent to platinum, capable of withstanding attack by dilute sulfuric and hydrochloric acids, chloride solutions and most organic acids. However, titanium coating is corroded by concentrated acids.
Titanium Spray Coating Applications
Due to high resistance to corrosion by sea water, titanium and its alloys are used to make:
- Propeller shafts.
- Rigging.
- Heat exchangers in desalination plants.
- Heater-chillers for salt water reservoirs and aquariums.
- Aerospace parts.
- Housings and components of ocean-deployed surveillance and monitoring devices for science and the military.
Click on the following link for more information on the HVAF STi System for Spraying Titanium.
