Effects of annealing temperature on the microstructure and hardness of TiAlSiN hard coatings

Abstract

TiAlSiN hard coatings were synthesized on high-speed steel using an arc ion enhanced magnetic sputtering hybrid system. The microstructure and hardness of the coatings at different annealing temperatures were explored by means of XRD, TEM, EDAX and Vickers indentation. The as-deposited TiAlSiN coatings were confirmed to be amorphous due to high depositing rate and low deposition temperature during the film growth. The transformation from amorphous to nanocomposites of nano-crystallites and amorphousness were observed after the annealing treatment, the microstructure of TiAlSiN coatings annealed at 800°C and 1000°C were consisted of crystalline hcp-AlN, fcc-TiN and amorphous phase, however, the coatings were only consisted of fcc-TiN and amorphous phase when annealing at 1100°C and 1200°C. Meanwhile, the formation of Al 2 O 3 was detected on the coating surface after annealing at 1200°C and it indicated the excellent oxidation resistance of the TiAlSiN coatings under the present experimental conditions. Furthermore, the average grain size of the TiAlSiN coatings after high temperature annealing even at 1200°C was less than 30 nm and the size increased with the increasing temperature. However, the hardness of the so-deposited coatings with HV 0.2N =3300 dramatically decreased with the increase of temperature and reached nearly to the hardness of TiN coatings with HV 0.2N =2300. arc ion enhanced magnetic sputtering, annealing treatment, microstructure, hardness, TiAlSiN hard coatings Citation: Wang X, Xu J H, Ma S L, et al. Effects of annealing temperature on the microstructure and hardness of TiAlSiN hard coatings. Ti-X-N (X=V, Al, W, Si, C, B, etc.) ceramic hard coatings had been investigated and proved to be with excellent properties by adding different metal or nonmetal elements in TiN matrix [1-6]. For example, TiAlN coatings improved film hardness and improved the oxidation temperature of TiN coatings from 550°C to 800°C, which resulted from the formation of dense Al 2 O 3 microfilm on top of the TiAlN coating. The dense Al 2 O 3 layer effectively inhibited further diffusions of O atoms from top to inside of the coatings [7,8]. Adding Si into TiN lattice could inhibit grains growth in columnar manners and contributed to the formation of nanocomposite microstructure composed of TiN crystallites in nanometer embedded in amorphous Si 3 N 4 matrix under thermodynamic driven conditions. The properties of TiSiN coatings were considerably improved due to nanocomposite structure such *Corresponding author (email: alexwx@mailst.xjtu.edu.cn) as superhardness (40-105 GPa) and high thermal stability (up to 1000°C) [9-11].Recently multi-components TiAlSiN coatings had been synthesized to achieve better performance than both TiAlN and TiSiN coatings by different approaches such as magnetron sputtering, arc ion plating and other composite technologies [12][13][14][15][16]. The investigations on TiAlSiN hard coatings were focused on the optimization of deposition process and relationships among composition, microstructure and...

Increasing Tool Life by AlCrTiSiN Film

“…The reason for the high adhesion strength of AlCrTiSiN film would be from addition of Si into AlCrTiN lattice. As reported by [7][8][9], adding Si into AlCrTiN lattice resulted in two important effects. The first effect is that it could decrease grain growth (small grain size) in columnar direction (columnar grain), resulting in higher strengthening [2,10,11].…”

“…The second effect is that it contributed to the formation of nanocomposite microstructure composed of AlCrTiN crystallites in nanometer embedded in amorphous Si 3 N 4 matrixes. This contribution significantly enhances hardness and strength of nanocomposite film [7][8][9]. The tool life performance of uncoated end mill and AlCrTiSiN coated end mill were presented by the plot of the maximum flank wear versus the cutting length as shown in Figure 2.…”

High-temperature oxidation behaviour of AlTiSiN and AlCrSiN coatings

“…With the annealing temperature increased to 800°C, the intensity of Ti(Al)N (200) diffraction peak was obviously enhanced. Weak diffraction peaks of AlN appeared, indicating that the crystallinity of AlTiSiN was increased during the annealing process [32]. At 900°C, the diffraction peak of Ti(Al)N (200) became weaker.…”

Improvement on thermal stability of TiAlSiN coatings deposited by IBAD

“…Because amorphous Si 3 N 4 prevents the formation of disruptions and increases grain boundaries between phases, the hardness, and mechanical properties of the TiAlSiN coating are dramatically improved [30]. The amorphous Si 3 N 4 plays an important role in resisting oxidation [31,32]. Thus, maintaining the Si 3 N 4 phase in TiAlSiN is important.…”