TiN Multilayer Coatings Research Articles

Residual Stress of TiN Multilayer Coatings Alternately Deposited by Arc Ion Plating and Magnetron Sputtering

Residual Stress of TiN Multilayer Coatings Alternately Deposited by Arc Ion Plating and Magnetron Sputtering

Microstructure and corrosion behavior of TiC/Ti(CN)/TiN multilayer CVD coatings on high strength steels

Titanium carbide/titanium carbonitride/titanium nitride (TiC/Ti(CN)/TiN) multilayer coatings are prepared on the surface of three high-strength steels (35CrMo, 42CrMo, and 40CrNiMo) by chemical vapor deposition method. The fracture morphology, elemental distribution, phase composition, micro-hardness, and adhesion of the multilayer film are analyzed. The hydrogen sulfide stress corrosion resistance of the coating is evaluated by the National Association of Corrosion Engineers saturated hydrogen sulfide solution immersion test. A test simulating the environment of the natural gas wells with high temperature and pressure in Luojiazhai in Sichuan is also performed. The results show that the multilayer coatings have dense structures, ∼11μm thickness, 24.5±2.0GPa nano-hardness, and ∼70N adhesion. The corrosion sample also shows no brittle failure induced by stress corrosion after treatment with the coating. Gravimetric analysis shows that the deposition of TiC/Ti(CN)/TiN multilayer coatings results in a corrosion rate reduction of at least 50 times compared with the high-strength steel substrate. A preliminary analysis on this phenomenon is conducted.

Comparison of the mechanical performance of cutting tools coated by either a TiC xN 1 − x single-layer or a TiC/TiC 0.5N 0.5/TiN multilayer using the hollow cathode discharge ion plating method

TiC xN 1 − x single-layer (x = 0–1.0) and TiC/TiC 0.5N 0.5/TiN multilayer coatings prepared using the hollow cathode discharge (HCD) ion plating method were investigated to improve the mechanical performance of high speed steel cutting tools. The carbon/nitrogen ratio of the TiC xN 1 − x coating was controlled by adjusting the composition of an additional acetylene/nitrogen mixture gas during the ion plating process. The mechanical performance characteristics of the coated cutting tools, such as the surface hardness, adhesion, wear and dynamic hardness, were studied. The cutting tools coated by the multilayer films showed higher wear resistance and longer use life than those coated by TiC xN 1 − x single-layer films. The higher dynamic hardness of the multilayer coatings was considered the primary contributor to the improvement of the mechanical properties.

Adhesion and Corrosion Resistance Properties of TiC/Ti(CN)/TiN Multilayer CVD Coatings on 42CrMo Steels

The TiC/Ti(CN)/TiN multilayer coatings were deposited on 42CrMo steel by chemical vapor deposition (CVD) method. The fracture morphology,structure,microhardness and adhesion of the coatings were analyzed. The immersion test in simulant solution with H2S,CO2 at 100°C and electrochemistry test in 20wt% H2SO4 at room temperture were applied to investigate the corrosion resistance of the multilayer films.The results reveal that the multilayer coatings can offer 42CrMo steel higher corrosion resistance,especially the immersion corrosion test.The corrosion rate of the samples coated with CVD multilayer films is reduced more 70 times than that of the uncoated and samples by quenching-polishing-quenching (QPQ) treat.

Deformation mechanisms of TiN multilayer coatings alternated by ductile or stiff interlayers

TiN multilayers that alternate with either titanium (ductile) or nanocomposite TiSiN (hard) interlayers were surface coated by filtered arc deposition onto stainless steel substrates. Hardness and deformation mechanisms of these multilayer coatings were investigated using depth-sensing indentation in comparison with traditional monolithic TiN coatings. A dual ion/electron beam microscope was used to analyse subsurface indentation damage. It was found that microstructural layering and the presence of interlayers in TiN multilayers jointly provided resistance to deformation by intercolumnar shear sliding, observed more evidently in the monolithic TiN coatings. This resulted in an increase in hardness, which also increased with both the number of layers and the presence of interlayers. Calculations based upon a mechanistic-based model revealed that the resistance by interlayers played a more important role than an increase in intergranular shear area due to the layered structure in resisting deformation. Compared with the titanium interlayer, the use of a hard nanocomposite interlayer increased the resistance to deformation; however, cracking occurred within both the TiN layers and the nanocomposite interlayers.

Synthesis and characterization of CN x/TiN multilayers on Si(100) substrates

CN x /TiN multilayer coatings were deposited onto Si(100) substrates by using the reactive closed-field unbalanced magnetron sputtering method. Different bilayer thicknesses ( B T) were attained by varying the substrate rotation speed during the deposition process. The focus of this work was a collective investigation of the bonding states and structure of the multilayer by means of X-ray photoelectron spectroscopy (XPS), high-angle X-ray diffraction (XRD), and low-angle X-ray scattering (LXRD). The characteristic of the layer was also confirmed by transmission electron microscopy (TEM), root-mean-square (RMS) surface roughness by atomic force microscopy (AFM). Chemical states such as TiN, TiO 2, and TiC exist in the TiN layer. The CN x layer consisted of C, N and Ti in which N is bonded with C in the forms of C N and C N. The RMS surface roughness of the multilayers significantly varied with the substrate rotation speed. The RMS surface roughness was between 0.7 and 1.4 nm. The hardness of CN x /TiN multilayer was highly dependent on their bilayer thickness. This multi-layer structure demonstrated an enhanced microhardness with decreasing bilayer thickness. It is found that for smaller bilayer thicknesses, the microhardness reproducibly achieved is as high as ∼50 GPa. In addition, stress measurement on the CN x /TiN multilayer is also conducted. The internal (compressive) stress is associated with the hardness of the multilayer. For the maximum hardness the stress is found to be ∼7.7 GPa. Moreover, pin-on disc test under dry condition showed low friction coefficient (0.11).

Stress analyses and in-situ fracture observation of wear protective multilayer coatings in contact loading

A model was developed to describe stress distributions in hard multilayer coatings under applied contact load, simulating coating application for wear protection. Elastic deformations were considered and an algorithm was suggested to calculate normal and shear stress across the coating thickness for various numbers of layers and layer thickness. The model was applied to analyze contact stress in Ti–TiN multilayer coatings produced by vacuum arc deposition. Calculated locations of maximum shear stress agreed well with locations of actual coating failures, which were studied in-situ using a scanning electron microscope (SEM). A three-point bending test stage was designed for SEM observations of deformation and crack development under a cylindrical indenter. Results indicated that the highest shear stress occurs under the substrate/coating interface and that this region may plastically deform causing coating adhesive and cohesive failure. When using a multilayer coating design with 10 pairs, the peak stress was moved into the coating volume, reducing normal and shear stresses in the substrate by as much as 40 and 22%, respectively. A good correlation between computational and experimental studies verified the model applicability for optimizing the design of hard multilayer coatings in tribological contacts.

Improvement of mechanical properties of Ti/TiN multilayer film deposited by sputtering

Advanced functional (multi-layer) coatings, were conducted by r.f. magnetron sputtering. Ti–TiN multi-layer coatings were deposited on a silicon (100) by using multi cathodes. The total thickness was kept at 150 nm and the number of layers was changed from 4 to 40. The relief of internal stress in a film, which causes breaking of the film, and formation of a preferred orientation of the film by increasing the number of layers, was confirmed by measurements of scratching, nano-indenting tests and XRD. These phenomena were explained by minimization of total energy composed of interface and strain energies. The preferred orientation was predicted to change from (111) to (100) with increasing layer number, and XRD produced the expected result.

Optimum multilayer TiN–TiCN coatings for wear resistance and actual application

This work employed the PVD process to deposit coatings of single layer TiN, binary layer TiN/TiCN, multilayer TiN\\Ti\\TiN and sequenced TiN\\TiCN\\TiN multilayer coatings with variable individual TiN and TiCN layers' thickness on tungsten carbide disks and inserts. Also investigated herein were the fracture mechanisms and the influence of sequence and thickness of these coatings on cylinder-on-disk line contact wear mode and ball-on-disk point contact wear mode through SRV reciprocating wear tests. Actual milling tests were also performed to identify the wear performance. Experimental results indicate that the coating with a total thickness of 7 μm and layer sequence TiN/TiCN/TiN exhibits good wear resistance on SRV wear test and milling test. The thickest multilayer TiN/Ti/TiN coating, although having the highest hardness, has the worst wear resistance for all tests. Notably zero-wear performance was observed for all coating disks under cutting fluid lubricated condition due to the transferred layers formed between the contact interface.

Examination of mechanical properties and failure mechanisms of TiN and Ti−TiN multilayer coatings

A number of studies have been carried out to establish mechanical properties of single and multilayer hard coatings. However, the mechanisms of deformation, cracking and delamination of coatings under ploughing and shear stress are not fully understood. A fractured cross-sectional specimen preparation technique through hardness indentation and scratch tests on hard coatings has been used in conjunction with high resolution SEM to observe deformation and fracture behaviour occurring as a result of these tests. TiN and Ti−TiN multilayer coatings were deposited on M2 high speed steel and silicon substrates using an unbalanced magnetron sputtering system. Hardness measurements and scratch tests were performed to monitor the mechanical properties. X-ray diffraction was used for phase identification. Coatings comprising fine columnar TiN behaved like closely congregated strong fibres: they were found to accommodate a large amount of ploughing and shear stress through densification and shear deformation. On increasing the load above a certain value, rupture of heavily deformed TiN initiated at defect locations and the cracks propagated and coalesced into macrocracks. When the applied load was increased to near the critical load, close packed columns separated from each other and detached from the substrate, resulting in total failure. For Ti−TiN multilayers, hardness and critical load are related to the different monolayer thickness of the Ti and TiN. The Ti layers dissipate most of the energy by means of shear deformation during the scratch test. At higher scratch loads, cracks occurred at Ti−TiN interfaces or at multilayer- substrate interfaces depending on the relative interface strengths. The influences of substrate hardness on the indentation crack pattern and scratch failure mechanism are also briefly covered in this paper.