Examination of residual stress, morphology and mechanical properties of sputtered TiN films

The mechanical properties of TiN films deposited on carbon steel JIS S45C by reactive dc magnetron sputtering under three sputtering gas pressures, 0.5Pa, 0.8Pa, and 1.76Pa were investigated. The residual stress once increased and then decreased with increasing bias voltage at 0.5Pa and 0.8Pa, but increased monotonously at 1.76Pa. These variations could be explained by the variations of the bombarding energy of a sputtered ion at each gas pressure. The variations of hardness and toughness correlated with the variation of residual stress. The variation of adhesive strength also could be explained by the variation of the bombarding energy with a model proposed in this study. A specific wear rate was also investigated, and it was found that to increase not only the hardness but also the adhesive strength is necessary to improve the wear resistance of TiN films.

Download Full-text

Residual Stress, Mechanical Properties, and Grain Morphology of Ti-6Al-4V Alloy Produced by Ultrasonic Impact Treatment Assisted Wire and Arc Additive Manufacturing

Metals ◽

10.3390/met8110934 ◽

2018 ◽

Vol 8 (11) ◽

pp. 934 ◽

Cited By ~ 5

Author(s):

Yichong Yang ◽

Xin Jin ◽

Changmeng Liu ◽

Muzheng Xiao ◽

Jiping Lu ◽

...

Keyword(s):

Mechanical Properties ◽

Residual Stress ◽

Additive Manufacturing ◽

Stress Reduction ◽

Grain Morphology ◽

Effective Technique ◽

Ultrasonic Impact Treatment ◽

Columnar Grains ◽

Equiaxed Grains ◽

Morphology And Mechanical Properties

Ultrasonic Impact Treatment (UIT) is an effective technique for surface refinement and residual stress reduction, which is widely used in welding. This study investigates UIT-assisted Wire and Arc Additive manufacturing (WAAM). The residual stress, grain morphology and mechanical properties of post-UIT and as-deposited samples are studied. The result demonstrates that the UIT has a significant influence on the decrease of the residual stress. Moreover, the residual stress of the post-UIT samples is much lower than that of the as-deposited samples. The samples fabricated by UIT-assisted WAAM have a novel, bamboo-like distribution of prior-β grains, an alternating distribution of short columnar grains and equiaxed grains. The grain size of this bamboo-like structure is much smaller than the coarsen columnar grains. In addition, the mechanical properties of the post-UIT and as-deposited samples are compared. The results indicate that the average tensile strength of the post-UIT samples is higher, while the average elongation of the post-UIT samples is lower.

Download Full-text

Mechanical testing and microstructural characterisation of TiN thin films

MRS Proceedings ◽

10.1557/proc-505-617 ◽

1997 ◽

Vol 505 ◽

Author(s):

A. Karimi ◽

O. R. Shojaei ◽

J. L. Martin

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Residual Stress ◽

Silicon Nitride ◽

Titanium Nitride ◽

Young’S Modulus ◽

Young's Modulus ◽

Bulge Test ◽

Tin Films ◽

Deposition Parameters

ABSTRACTMechanical properties of titanium nitride (TiNx) thin films have been investigated using the bulge test and the depth sensing nanoindentation measurements. The bulge test was performed on the square free standing membranes made by means of standard micromachining of silicon wafers, while the nanoindentation was conducted on the films adhered to their supporting substrate. Thin layeres of titanium nitride (t = 300 – 1000 nm) were deposited in a r. f. magnetron sputtering system on the Si(100) wafers containing a layer of low stress LPCVD silicon nitride (SiNy). The bulge test was first conducted on the silicon nitride film to determine its proper residual stress and Young's modulus. Then, the composite membrane made of TiNx together with underlying silicon nitride was bulged and the related load-displacement variation was measured. Finally, using a simple rule of mixture formula the elastic mechanical properties of TiNx coatings were calculated. Both the Young's modulus and residual stress showed increasing values with negative bias voltage and nitrogen to titanium ratio, but the substrate temperature between 50–570°C was found less significant as compared to the other parameters. Nanoindentation data extracted from dynamically loading-unloading of TiN films converged to the bulge test measurements for compact coatings, but diverged from the bulge test data for porous coatings. Scanning electron microscopy observation of the cross sectioned specimens showed that TiN films first grow by formation of the nanocrystallites of size mostly between 10 – 15 nm. These nanocrystallites give rise to the columnar morphology beyond a thickness of 50–100 nm. The columns change their aspect with deposition parameters, but remain nearly perpendicular to the film surface. Relationship between microstructural evolution of columns and mechanical properties of coatings are discussed in terms of deposition parameters.

Download Full-text