We review results on the growth of metastable Ti1−xAlxN alloy films by hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS/DCMS) using the time domain to apply substrate bias either in ...synchronous with the entire HIPIMS pulse or just the metal-rich portion of the pulse in mixed Ar/N2 discharges. Depending upon which elemental target, Ti or Al, is powered by HIPIMS, distinctly different film-growth kinetic pathways are observed due to charge and mass differences in the metal-ion fluxes incident at the growth surface. Al+ ion irradiation during Al–HIPIMS/Ti–DCMS at 500°C, with a negative substrate bias Vs=60V synchronized to the HIPIMS pulse (thus suppressing Ar+ ion irradiation due to DCMS), leads to single-phase NaCl-structure Ti1−xAlxN films (x≤0.60) with high hardness (>30GPa with x>0.55) and low stress (0.2–0.8GPa compressive). Ar+ ion bombardment can be further suppressed in favor of predominantly Al+ ion irradiation by synchronizing the substrate bias to only the metal-ion-rich portion of the Al–HIPIMS pulse. In distinct contrast, Ti–HIPIMS/Al–DCMS Ti1−xAlxN layers grown with Ti+/Ti2+ metal ion irradiation and the same HIPIMS-synchronized Vs value, are two-phase mixtures, NaCl-structure Ti1−xAlxN plus wurtzite AlN, exhibiting low hardness (≃18GPa) with high compressive stresses, up to −3.5GPa. In both cases, film properties are controlled by the average metal-ion momentum per deposited atom transferred to the film surface. During Ti–HIPIMS, the growing film is subjected to an intense flux of doubly-ionized Ti2+, while Al2+ irradiation is insignificant during Al–HIPIMS. This asymmetry is decisive since the critical limit for precipitation of w-AlN, 135 eV-amu1/2, is easily exceeded during Ti–HIPIMS, even with no intentional bias. The high Ti2+ ion flux is primarily due to the second ionization potential (IP2) of Ti being lower than the first IP (IP1) of Ar. New results involving the HIPIMS growth of metastable Ti1−xAlxN alloy films from segmented TiAl targets are consistent with the above conclusions.
•Ti1−xAlxN alloys with high hardness and low residual stress are demonstrated.•Hybrid HIPIMS/DCMS approach with opposing metal targets is used.•Film growth pathways depend upon which metal target is powered by HIPIMS.•Al–HIPIMS/Ti–DCMS alloys have a much higher solid-solubility limit, xmax=0.64.•Low mass and single charge of the Al+ ion permit tuning properties of metastable cubic Ti0.38Al0.62N by adjusting Vs.
A hybrid deposition process consisting of reactive high-power pulsed and dc magnetron cosputtering (HIPIMS and DCMS) from Ti and Al targets is used to grow Ti1−xAlxN alloys, with x~0.6, on Si(001) at ...500°C. Two series of films are deposited in which the energy and momentum of metal ions incident at the growing film are individually varied. In both sets of experiments, a negative bias Vs ranging from 20 to 280V is applied to the substrate in synchronous, as determined by in-situ mass spectrometry, with the metal-ion-rich part of the HIPIMS pulse. Ion momentum is varied by switching the HIPIMS and dc power supplies to change the mass m and average charge of the primary metal ion. Al-HIPIMS/Ti-DCMS layers grown under Al+ (mAl=26.98amu) bombardment with 20≤Vs≤160V are single-phase NaCl-structure alloys, while films deposited with Vs>160V are two-phase, cubic plus wurtzite. The corresponding critical average metal-ion momentum transfer per deposited atom for phase separation is 〈pd⁎〉≥135 eV-amu1/2. In distinct contrast, layers deposited in the Ti-HIPIMS/Al-DCMS configuration with Ti+/Ti2+ (mTi=47.88amu) ion irradiation are two-phase even with the lowest bias, Vs=20V, for which 〈pd⁎〉>135 eV-amu1/2. Precipitation of wurtzite-structure AlN is primarily determined by the average metal-ion momentum transfer to the growing film, rather than by the deposited metal-ion energy. Ti-HIPIMS/Al-DCMS layers grown with Vs=20V are two-phase with compressive stress σ=−2GPa which increases to −6.2GPa at Vs=120V; hardness H values range from 17.5 to 27GPa and are directly correlated with σ. However, for Al-HIPIMS/Ti-DCMS, the relatively low mass and single charge of the Al+ ion permits tuning properties of metastable cubic Ti0.38Al0.62N by adjusting Vs to vary, for example, the hardness from 12 to 31GPa while maintaining σ~0.
•High AlN-content TiAlN films are grown using a hybrid HIPIMS/DCMS.•The average metal-ion momentum transfer per deposited atom determines phase content.•Layers grown with Ti+/Ti2+ ion irradiation are two-phase for each substrate bias Vs.•Layers grown under Al+ bombardment with Vs≤160V are single-phase cubic alloys.
Although spinodal decomposition of metastable cubic Ti1−xAlxN-based coatings and the underlying mechanisms are widely understood, investigations on the influence of high deposition temperatures are ...lacking. It is thus the aim of this work to elucidate structure, properties, thermal stability and wear performance of Ti1−xAlxN/TiN multilayer coatings sputter deposited on powder-metallurgical high-speed steels at substrate temperatures between 375 and 575°C. At higher substrate temperatures, sharper column boundaries and sharper transition zones in the multilayer arrangement yield increased hardness in the as-deposited state, while the detrimental formation of wurtzite AlN during vacuum annealing is retarded by 50°C according to Rietveld refinement of X-ray diffractograms. Tribological tests at room temperature and up to 650°C corroborate the high potential of increased coating temperatures, while demonstrating the crucial importance of using a substrate material with adequate hot hardness. Cutting tests with coated high-speed steel end mills verify the high temperature deposition approach showing a tool life increase of ~40%.
•High deposition temperatures yield enhanced mechanical and tribological properties.•Strengthening due to sharper interfaces despite rising domain sizes•Spinodal decomposition and wurtzite AlN formation retarded by 50°C•Influence of substrate material's hot hardness on tribological load bearing capacity•Cutting tests reveal a tool life increase of ~40%.
Recently, carbide-free alloying systems with yield strength Rp0.1 of up to 4000MPa and outstanding thermal stability are available, which offer the possibility to elevate coating deposition ...temperatures up to 600°C. The present work demonstrates that the limited Ti1−xAlxN coating adhesion on a Fe–25%Co–15%Mo grade caused by the absence of carbides in the substrates can be significantly improved from HF 4 to HF 2 in the Rockwell adhesion test by plasma-assisted nitriding during sputter etching. X-ray photoelectron spectroscopy measurements reveal that the nitrogen diffusion zone is confined to the first few nanometre of the substrate surface, while mainly Mo–N and partly Fe–N bondings are formed. X-ray diffraction exhibits the formation of cubic Mo2N in the nitrided layer. The coatings show a single-phase face-centered cubic Ti1-xAlxN structure tending to a preferred (110) growth orientation with increasing nitriding time. Tribological tests performed at room temperature and 650°C indicate superior wear performance of duplex Ti1-xAlxN coated Fe–25%Co–15%Mo.
► Industrial scale Ti1-xAlxN sputter deposition on novel Fe–Co–Mo tool material. ► Development of duplex process yielding significant adhesion enhancement. ► Determination of chemical bonding state in a nanometre-scale diffusion zone. ► Rietveld refined XRD investigation evidencing Mo2N formation. ► Auspicious tribological properties with low wear rates.
In industrial PVD deposition systems the substrates usually move in a so-called planetary rotation in order to deposit a homogeneous coating on the whole surface area of the tools. In this study we ...compared microstructure, surface topography and hardness of the coatings, deposited in the same batch but using different types of rotation: one-fold, two-fold and three-fold. The coating was a multilayer TiAlN/VN, deposited by magnetron sputtering. Microstructure was studied on cross-sectioned samples using SEM, prepared either by fracture or by focused ion beam. Coatings prepared by two-fold and three-fold rotation were very similar, both in microstructure and in hardness. They had dense, only slightly columnar microstructure. In contrast, coatings prepared by single rotation had a pronounced columnar microstructure, and substantially lower hardness.
► TiAlN/VN hard coatings were deposited using one-, two- and three-fold rotation. ► Microstructure extends from strong columnar in one-fold to dense in three-fold rotation. ► Hardness is comparable in two- and three-fold rotation, but much lower in one-fold. ► Deformation during indentation is achieved by shearing of individual columns.
Micro-crystalline diamond (MCD) coatings were deposited on cemented carbide inserts at different temperatures using hot filament chemical vapor deposition technique. For investigating the effect of ...the developed diamond crystallinity on the fatigue strength and wear behaviour of the prepared MCD coated inserts, inclined impact tests and milling investigations were conducted correspondingly. Raman spectra were recorded for capturing the crystalline phases after the film deposition and their potential changes after the impact and milling experiments induced by the mechanical and thermal loads. Thus, the explanation of the cutting performance of the employed diamond coated inserts with various crystalline phases was enabled.
Die Beschichtung von Zerspanwerkzeugen hat in der Vergangenheit entscheidend zu Verbesserungen und Leistungssteigerungen in der Zerspantechnik beitragen können. Aluminiumoxid (Al2O3) nimmt hierbei ...aufgrund einer Vielzahl an Eigenschaften, wie Warmhärte, Oxidations‐, Diffusions‐ und chemischer Beständigkeit eine wichtige Rolle ein. Physical Vapor Deposition (PVD) Al2O3‐Beschichtungen, die mittels medium frequency Magnetron Sputtering (mfMS) hergestellt werden, haben ihre Leistungsfähigkeit in der Zerspanung von schwer zerspanbaren Werkstoffen bereits bewiesen. Die High Power Pulsed Magnetron Sputtering (HPPMS)‐Technologie kann zu weiteren Verbesserungen der Schichtmorphologie und ‐eigenschaften aufgrund hoher Ionisation des abgesputterten Materials führen. In diesem Zusammenhang ist die Abscheidung von Al2O3 mittels HPPMS bisher wenig erforscht. Bisher ist noch unklar, welche Phasen abgeschieden werden bzw. wie die Prozessparameter die Phasenbildung beeinflussen. Ziel der Untersuchungen ist es, die Erkenntnisse über die Abscheidung von PVD‐Al2O3‐Schichten und deren Einsatzverhalten auf die industrielle Ebene mittels HPPMS zu übertragen, neue Einsatzbereiche des potenzialträchtigen Schichtsystems zu erschließen und somit einen Beitrag zur Weiterentwicklung in der Zerspantechnik von schwer zerspanbaren Werkstoffen zu leisten.
Abstract
Die Beschichtung von Zerspanwerkzeugen hat in der Vergangenheit entscheidend zu Verbesserungen und Leistungssteigerungen in der Zerspantechnik beitragen können. Aluminiumoxid (Al
2
O
3
) ...nimmt hierbei aufgrund einer Vielzahl an Eigenschaften, wie Warmhärte, Oxidations‐, Diffusions‐ und chemischer Beständigkeit eine wichtige Rolle ein. Physical Vapor Deposition (PVD) Al
2
O
3
‐Beschichtungen, die mittels medium frequency Magnetron Sputtering (mfMS) hergestellt werden, haben ihre Leistungsfähigkeit in der Zerspanung von schwer zerspanbaren Werkstoffen bereits bewiesen. Die High Power Pulsed Magnetron Sputtering (HPPMS)‐Technologie kann zu weiteren Verbesserungen der Schichtmorphologie und ‐eigenschaften aufgrund hoher Ionisation des abgesputterten Materials führen. In diesem Zusammenhang ist die Abscheidung von Al
2
O
3
mittels HPPMS bisher wenig erforscht. Bisher ist noch unklar, welche Phasen abgeschieden werden bzw. wie die Prozessparameter die Phasenbildung beeinflussen. Ziel der Untersuchungen ist es, die Erkenntnisse über die Abscheidung von PVD‐Al
2
O
3
‐Schichten und deren Einsatzverhalten auf die industrielle Ebene mittels HPPMS zu übertragen, neue Einsatzbereiche des potenzialträchtigen Schichtsystems zu erschließen und somit einen Beitrag zur Weiterentwicklung in der Zerspantechnik von schwer zerspanbaren Werkstoffen zu leisten.
Translation abstract
Coating of cutting tools has been contributing to improvements and performance increases in the machining technology. Al
2
O
3
plays an important role due to its high hot hardness as well as high oxidation and diffusion resistance and chemical stability. Physical vapor deposition (PVD) aluminium oxide (Al
2
O
3
) coatings deposited by means of medium frequency magnetron sputtering (mfMS) have already proven their capabilities in the machining of hard‐to‐machine materials. The High Power Pulsed Magnetron Sputtering (HPPMS) technology could offer an improvement of the coating morphology and properties due to high ionization of the sputtered material. In this connection, deposition of the Al
2
O
3
by means of HPPMS is not fundamentally researched so far. It is still unclear which phases could be deposited and how the process parameters affect the phase formation. The aim of the investigations is to transfer the knowledge about the deposition of HPPMS‐Al
2
O
3
coatings and their application to the industrial level, to create new areas for promising coating systems and thus to contribute to the development of machining technology of the hard‐to‐machine materials.
Die Beschichtung von Zerspanwerkzeugen hat in der Vergangenheit entscheidend zu Verbesserungen und Leistungssteigerungen in der Zerspantechnik beitragen können. Aluminiumoxid (Al2O3) nimmt hierbei ...aufgrund einer Vielzahl an Eigenschaften, wie Warmhärte, Oxidations‐, Diffusions‐ und chemischer Beständigkeit eine wichtige Rolle ein. Physical Vapor Deposition (PVD) Al2O3‐Beschichtungen, die mittels medium frequency Magnetron Sputtering (mfMS) hergestellt werden, haben ihre Leistungsfähigkeit in der Zerspanung von schwer zerspanbaren Werkstoffen bereits bewiesen. Die High Power Pulsed Magnetron Sputtering (HPPMS)‐Technologie kann zu weiteren Verbesserungen der Schichtmorphologie und ‐eigenschaften aufgrund hoher Ionisation des abgesputterten Materials führen. In diesem Zusammenhang ist die Abscheidung von Al2O3 mittels HPPMS bisher wenig erforscht. Bisher ist noch unklar, welche Phasen abgeschieden werden bzw. wie die Prozessparameter die Phasenbildung beeinflussen. Ziel der Untersuchungen ist es, die Erkenntnisse über die Abscheidung von PVD‐Al2O3‐Schichten und deren Einsatzverhalten auf die industrielle Ebene mittels HPPMS zu übertragen, neue Einsatzbereiche des potenzialträchtigen Schichtsystems zu erschließen und somit einen Beitrag zur Weiterentwicklung in der Zerspantechnik von schwer zerspanbaren Werkstoffen zu leisten.
Translation
Coating of cutting tools has been contributing to improvements and performance increases in the machining technology. Al2O3 plays an important role due to its high hot hardness as well as high oxidation and diffusion resistance and chemical stability. Physical vapor deposition (PVD) aluminium oxide (Al2O3) coatings deposited by means of medium frequency magnetron sputtering (mfMS) have already proven their capabilities in the machining of hard‐to‐machine materials. The High Power Pulsed Magnetron Sputtering (HPPMS) technology could offer an improvement of the coating morphology and properties due to high ionization of the sputtered material. In this connection, deposition of the Al2O3 by means of HPPMS is not fundamentally researched so far. It is still unclear which phases could be deposited and how the process parameters affect the phase formation. The aim of the investigations is to transfer the knowledge about the deposition of HPPMS‐Al2O3 coatings and their application to the industrial level, to create new areas for promising coating systems and thus to contribute to the development of machining technology of the hard‐to‐machine materials.
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