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Thermic Edge Ltd is the sole manufacturer of high purity Cubic Silicon Carbide (SiC3) and Cubic Titanium Carbide (TiC3) ceramic coatings, that can be applied to purified graphite, ceramics and refractory metal components.
Thermic Edge has developed a dense high purity titanium carbide coating with a cubic structure, trade name TiC3, to protect graphite in high temperature high vacuum environments. With vapour pressures 3 orders less for TiC3 when compared to SiC the material goes beyond our SiC3 in protection in vacuum and high temperature environments (Not suitable for O2 environments).
Thermic Edge Coatings is the sole manufacturer of TiC3, short for Cubic Titanium Carbide. The CVD deposition process combines high growth rate, controlled crystal size, isotropic structure and low surface roughness.
Layer thickness can be varied but typically a layer of 50 – 100µm is applied.
The coating can be applied to graphite parts to be used in semiconductor, aerospace and heating technologies. The combination of graphite selection and graphite machining expertise developed by Thermic Edge Coatings will ensure that customers experience optimal support for various critical components.
Thermic Edge’s state of the art machine shop allows us to offer a complete solution including manufacture of the base graphite component, and the TiC3 ceramic coating. We also offer a coating only service for customer supplied parts. This coating is best suited to high expansion graphites such as Poco DFP2.
TiC3 Cubic Titanium Carbide ceramic coating can be used at high temperature in the following environments:
| Property | Value |
| Density | 4930 kg.m-3 |
| Crystal Structure | 3C (cubic; β) |
| Porosity | 0% (helium leak tight) |
| Crystal Size | 2-10 µm |
| Visual Appearance | Light grey, Satin |
| Thermal Expansion (RT – 400°c) | 7.7 X 10-6M.k-1 |
| Thermal Conductivity (@20°C) | 50 W.m-1K-1 |
| Elastic Modulus | 420GPa |
| Electrical Resistivity (@20°C) | 0.02Ω.m |
| Hardness (Vickers) | 3500 HV |
An XRD Diagram is shown here.
The peaks shown in the diagram perfectly match the 3C crystal structure.
Surface and fracture as observed with Scanning Electron Microscope are shown below
The porosity of graphite is covered very well, and the coating penetrates the open porosity and enhances a very good adherence of the coating on the graphite surface. Adherence on sharp edges is good but in all cases a radius of at least 0.2 mm is advised.
Use of graphite coated parts in high end applications depends on overall coverage of the graphite. This is important for the outside surfaces as well as for small and larger holes (blind, through). The small hole in the satellite disc is a good example and sufficient coating on the inside is important.
At TEC we made a small graphite sample with small holes drilled into the side with a handheld drill. This is for a first assessment only and further testing will commence the coming weeks. The test piece is shown below and after drilling and coating smaller parts were broken of the piece to examine the hole internals.
SEM analysis of a hole shows clearly that the coting penetrates into the small hole dia1.2mm x 10.0 mm deep (see right).
At the bottom of the hole (diameter approximately 1.2 mm; depth 5.5 mm) there is still a layer of 10 µm present. Coating of the small satellite disc hole is therefore no problem and at least 60 % of the top layer thickness is expected at the bottom of the hole.
Currently we can coat components up to dia360 x 500mm.
Thermic Edge Coatings (TEC) deposits a high purity Titanium carbide coating on graphite. The cubic, TiC3, coating has excellent corrosion protective properties at low, medium and high temperature. Typically the coating finds application in semiconductor industry, vacuum furnaces and aerospace. Materials coated are graphite, carbon composites, various ceramics and refractory metals.
The coating can only protect the underlying material effectively when the coating covers all areas visible to the environment, when it adheres well to the material and does not crack after the coating process.
A well adhering coating is therefore essential and the process carried out by TEC accomplishes this on various materials. The process is carried out at high temperature using ultrapure gases amongst which hydrogen which cleans the surface by removing oxides and other contaminants which might hinder good adhesion. During the initial stages of the process there is a trade-off between deposition and etching which further cleans the interface between underlying material and coating.
Graphite is used as the underlying material which has a high porosity. The TEC process penetrates the pores in the graphite very well and gives it a further enhancement for the adhesion.
This table shows the impurities of TiC3 coating
Lowest limit of detection with this method. Testing carried out by EAG Laboratories using Glow Discharge Mass Spectroscopy.
Thermic Edge Limited are committed to lead the industry in delivering innovative, high-quality high-temperature applications, backed by unparalleled customer service.
To be a beacon of innovation and excellence, inspiring positive change and leaving a lasting impact on our industry and the environment
