Titanium diboride (TiB2) coatings of hexagonal crystal structure are very hard. In addition to the hardness in room temperature, TiB2 layers maintain its hardness and chemical inertness at elevated temperatures during the machining processes, even in contact with aluminum and its alloys. The most impressive points is: TiB2 coating layer keeps its high elastic modulus, compressive strength, and wear resistance at very high machining temperatures.
Therefore, coatings made of TiB2 layers are very popular and used in forming, tool cutting, injection molding and many other applications, where a superior tribological behavior is essential.
There are two things which are very critical when TiB2 coatings are applied for better performance.
1. Coating Process technology and
2. Target materials quality.
There are the two important parameters that directly influence the internal stress, coating microstructure, which are ultimately transform into coating properties and product functionalities during machining process.
Hardness higher than 4000 HV is often demanded by customers for TiB2 coatings.
While maintaining such high hardness, it is also very crucial to lower the elastic modulus to keep the wear resistance high. Apart from this, there are also several challenges remains intact when employing TiB2 material for industrial applications with high scalability in particular fracture toughness, compressive stress and poor adhesion, which require the careful selection of process technology and quality of target materials.
TiB2 targets for HiPIMS coating equipment
TiB2 has also been incorporated into multilayer coatings or as a single-layer coatings by Physical Vapor Deposition (PVD) process. Among all other PVD processes, ion assisted PVD (i-PVD) process are more popular, as the impacting of energetic ions on the coating layers enable the process engineer to control the microstructure and stress levels of the coatings.
Using a low-quality TiB2 targets, the off-stoichiometric TiB2 coatings are produced with intense and distinct columnar microstructure and crystallographic texture. Both boron rich and boron-deficient material makes the coatings unsuccessful in the machining process. Hence, a high quality TiB2 targets are necessary for better machining performance.
High Power Impulse Magnetron Sputtering technology (HiPIMS) based TiB2 coating process associated with a precisely manufactured ceramic TiB2 target material always bring TiB2 coating material with low stress and favorable crystal structure.
Coatings made using competitor’s target
Coatings made using Avaluxe’s target
Picture represents the performance of coatings undergone for the fifteen minutes of machining duration.
Test conditions: Vc = 80m/min; f= 0.2mm/rev.; ap=2mm; dry machining;
Also, TiB2 targets from Avaluxe have shown remarkable stability when operated in HiPIMS mode with the deposition powers higher than the competitor which allow our customer to speed up their manufacturing process with increased deposition rates, which were quite close to the ones reported by DCMS.
you can find our main article about TiB2 here