Thermal Shock and Oxidation Behavior of HiPIMS TiAlN Coatings Grown on Ti-48Al-2Cr-2Nb Intermetallic Alloy

Abstract

A High Power Impulse Magnetron Sputtering (HiPIMS) method for depositing TiAlN environmental barrier coatings on the surface of Ti-48Al-2Cr-2Nb alloy was developed in view of their exploitation in turbine engines. Three differently engineered TiAlN films were processed and their performance compared. Bare intermetallic alloy coupons and coated specimens were submitted to thermal cycling under oxidizing atmosphere up to 850 °C or 950 °C, at high heating and cooling rates. For this purpose, a burner rig able to simulate the operating conditions of the different stages of turbine engines was used. Microstructures of the samples were compared before and after each test using several techniques (microscopy, XRD, and XPS). Coating-intermetallic substrate adhesion and tribological properties were investigated too. All the TiAlN films provided a remarkable increase in oxidation resistance. Good adhesion properties were observed even after repeated thermal shocks. HiPIMS pretreatments of the substrate surfaces performed before the coating deposition significantly affected the oxidation rate, the oxide layer composition and the coating/substrate adhesion.

Oxidation resistance and thermal stability of a β-solidified γ-TiAl based alloy after nitrogen ion implantation

“…However, an increase in time at 550 • C or in annealing temperature (to 750 • C) gradually decreased the microhardness to 950-1000 HV. This is most likely caused by a combination of factors, including nitrides coarsening, loss of coherency of nitrides/matrix boundary, diffusion of nitrogen atoms from the surface into the bulk of the material, development of recovery processes, and partial relaxation of residual stresses in the layer [53][54][55]. It should be noted however, that the interlamellar spacing structure did not noticeably change during annealing at both temperatures (Fig.…”

Microstructure Evolution of Tin Coatings Prepared by Dual-Pulse Power Magnetron Sputtering

“…In recent years, high power impulse magnetron sputtering (HIPIMS), as an alternative to di-rect current magnetron sputtering (DCMS), has attracted extensive attention from many re-searchers and the industry (Purandare et al, 2020;Chen et al, 2019). It utilizes high peak target power and extremely low duty cycle to generate high-density plasma and highly ionized sputtered particles to improve the microstructure and mechanical properties of coatings (Badini et al, 2019;Wu et al, 2019). However, the deposition rate of transition metal nitride coatings deposited by HIPIMS is only 15%-50% compared with that of DCMS at the same average target power because the sputtered ions can be attracted back toward the cathodic target, low duty cycle and target poisoning (Lin et al, 2017;Bleykher et al, 2018).…”

The Geometric Surface Structure of EN X153CrMoV12 Tool Steel after Finish Turning Using PCBN Cutting Tools

“…TiAlN coating applied on cutting tools, which is a TiN improved by adding aluminum, provides higher, than TiN coating, resistance to oxidation at high temperatures [19]. TiN oxidation process takes place at about 400 • C., while TiAlN oxidizes at temperatures above 600 • C [20,21], which increases the TiAlN-coated tool life.…”

“…This affects the formation of the so-called a white layer on the chip surface, an example of which is shown in Figure 1. An example of a "white layer" on the chip surface after processing improved steel [21].…”

“…The above research was continued in many studies [28][29][30], extending it with a Vc variable cutting speed. CBN 7015 with a TiN coating was used as cutting materials (tested An example of a "white layer" on the chip surface after processing improved steel [21].…”