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1.
An investigation has been conducted to study wetting characteristics of aluminium towards different cutting tool materials for assessing the compatibility for dry machining of aluminum. For this purpose uncoated carbide (94%WC + 6%Co) and mono or multi-layer coated carbide tools with top coating of TiC, TiN, Al2O3 and diamond have been used. It was observed that aluminium had a tendency to wet uncoated carbide (94%WC + 6%Co) inserts. However, wetting was more pronounced when surface was enriched with cobalt. In contrast, wetting of aluminium was less when the WC content of the carbide tool surface increased. Coatings like TiC, TiN or Al2O3 could not show pure non-wetting characteristics for aluminium. The aluminium appeared to dissolve the coatings in different degrees. On the other hand, coating of diamond exhibited inertness towards aluminum leading to non-wetting behaviour. Turning test with aluminium indicated heavy material built up on uncoated (94%WC + 6%Co) tool. Built up edge formation could not be avoided when carbide inserts with a top coating of TiC, TiN, Al2O3 were engaged in machining of aluminium. However, the non-wetting characteristic of diamond coating was reflected during machining of aluminium. The chips slided smoothly over the rake face leaving no trace of edge built up. 相似文献
2.
Ti-Al-N coatings are well known for their excellent properties and age-hardening abilities. Here we show that the life-time of coated inserts during turning of stainless steel can be increased to 200% by post-deposition vacuum annealing at 900 °C combined with a ~ 1 K/min vacuum furnace cooling. During milling of 42CrMo steel an increase in tool life-time to 140% is only obtained if the cooling condition after annealing at 900 °C contains a fast segment with 50 K/min from 800 to 700 °C. Thereby, the Co-binder in cemented carbide exhibits a retarded phase transformation from cubic to hexagonal. Consequently, the fracture toughness of the cemented carbide is reduced only from ~ 10.8 to 10.4 MPa√m while the coating still has an adhesive strength of ~ 65 N.Our results indicate that best machining performances of coated inserts are obtained after annealing at 900 °C where the supersaturated Ti0.34Al0.66N coating undergoes spinodal decomposition to form nm-sized cubic TiN and AlN domains resulting in a hardness increase from 34.5 to 38.7 GPa. Additionally, we demonstrate that careful attention needs to be paid on the influence of annealing conditions on adhesive strength and fracture toughness of coated inserts. 相似文献
3.
Ti6242S and Ti-555, as two typical titanium alloys, are often used to manufacture high-temperature aeroengine parts and landing gear components, respectively. They have different chemical composition and microstructure, which make them have different mechanical properties, and also affect their machinability. In this paper, face milling experiments were carried out to evaluate the wear performance by using CVD-Ti(C, N) + Al2O3 + TiN, PVD-(Ti, Al)N + TiN coated and uncoated tools. The results show that Ti-555 has the worse machinability than that of Ti6242S. When milling Ti6242S, all tools suffered adhesive wear and diffusion wear; the wear of Ti(C, N) + Al2O3 + TiN coated tool was more serious than that of other tools due to the blunt cutting edge; (Ti, Al)N + TiN coated tool suffered micro chipping and coating peeling with the minimal wear loss. When milling Ti-555, uncoated tool suffered serious chipping, abrasive wear and adhesive wear; Ti(C, N) + Al2O3 + TiN coated tool suffered serious chipping and coating peeling with short tool life; (Ti, Al)N + TiN coated tool suffered coating peeling, adhesive wear and diffusion wear. Overall, (Ti, Al)N + TiN coated tools have the longest tool life and are preferred for face milling of Ti6242S and Ti-555 titanium alloys. 相似文献
4.
Multilayer TiN/TiCN/TiCN/TiC/TiN and TiN/TiCN/TiCN/TiC/Al2O3 hard coatings with total thicknesses of 15.7 μm and 9.3 μm were deposited on WC-10Co substrates using a chemical vapor deposition system. Evaluation of surface, cross-section morphologies, chemical composition and phases of coatings were analyzed by field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) analyses respectively. Corrosion properties were evaluated in 3.5 wt% NaCl medium using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Tribological properties of fabricated multilayer hard coatings were evaluated using pin-on-disk tests. Results show that active dissolution of the WC-10Co occurred while the coated samples showed more anodic slopes as well as lower corrosion current densities. The corrosion current densities of 3.3 × 10−7 A/cm2 and 7.5 × 10−8 A/cm2 were obtained for the TiN/TiCN/TiCN/TiC/TiN and TiN/TiCN/TiCN/TiC/Al2O3 coated specimens which are much lower than 4 × 10−6 A/cm2 of substrate. EIS analysis confirmed the results of potentiodynamic polarization curves. Delamination of the TiN coating and formation of titanium oxide compounds on the surface of the TiN/TiCN/TiCN/TiC/TiN coating revealed that oxidative wear mechanism is dominant for this sample, while adhesive wear mechanism was dominant for the TiN/TiCN/TiCN/TiC/Al2O3 coated sample. 相似文献
5.
Graded and multilayered AlxTi1−xN nanocrystalline coatings were synthesized by using cathodic-arc evaporation (CAE) process. Ti33Al67 and Ti50Al50 alloy cathodes were used for the deposition of AlxTi1−xN nanocrystalline coatings with different Al/(Ti+Al) ratios. Optical emission spectra of the plasma species including atomic and ionized Ti, atomic Al, excited and ionized nitrogen (N2 and N2+) revealed that the excitation, ionization and charge transfer reactions of the Al-Ti-N plasma occurred during the AlxTi1−xN coating process. A preferred (111) orientation was shown in the Al0.67Ti0.33N with high Al/(Ti+Al) atomic content ratio (0.63) and small grain size (29 nm). The graded Al0.67Ti0.33N/TiN possessed the highest hardness of Hv25 g 3850 ± 180. However, the multilayered Al0.67Ti0.33N/TiN coating supported a longer tool life with lower residual stress. It has been found that the wear performance and mechanical properties of the films were correlated with the Al/(Ti+Al) content ratio and multilayered structure. 相似文献
6.
The structure, mechanical properties, and machining performance of arc evaporated Ti-Al-O-N coatings have been investigated for an Al0.66Ti0.34 target composition and O2/(O2+N2) gas flow-ratio varied between 0 to 24%. The coating structure was analysed using SEM, EDX, XRD, XPS, TEM, and STEM. Mechanical properties were analysed using nanoindentation and the deformation behaviour was analysed by probing the nanoindentation craters. The coatings performances in cutting tests were evaluated in a turning application in low carbon steel (DIN Ck45). It is shown that the addition of oxygen into the arc deposition process leads to the formation of a dual layer structure. It consists of an initial cubic NaCl-structure solid solution phase formed closest to the substrate, containing up to 35 at.% oxygen (O/O+N), followed by steady-state growth of a nanocomposite compound layer comprised of Al2O3, AlN, TiN, and Ti(O,N). The addition of oxygen increases the ductility of the coatings, which improves the performances in cutting tests. At high levels of oxygen, (> 13 at.%), however, the performance is dramatically reduced as a result of increased crater wear. 相似文献
7.
High temperature tribological characterisation of TiAlSiN coatings produced by cathodic arc evaporation 总被引:2,自引:0,他引:2
Gonzalo G. Fuentes Eluxka Almandoz Rosario Martínez Jaume Caro 《Surface & coatings technology》2010,205(5):1368-1373
This study reports on the wear properties at medium-high temperatures of TiAlSiN films deposited by cathodic arc evaporation on hot work steel substrates. The chemical composition and microstructure of the coatings were characterised by glow discharge optical emission spectroscopy, scanning electron microscopy and X-ray diffraction. The mechanical properties, i.e. hardness and elastic modulus were evaluated by nanoindentation, and the adhesion of the coatings was tested by scratch tests. Coatings with stoichiometries of Ti0.31Al0.1Si0.06N0.53 and Ti0.23Al0.12Si0.09N0.55 exhibit microstructures consisting of solid solutions of (Ti,Al,Si)N, where Al and Si replace Ti atoms. These films show high hardness and good adhesion strength to the hot work steels. Conversely, coatings with a stoichiometry of Ti0.09Al0.34Si0.02N0.55 show a wurtzite-like microstructure, low hardness and poor adhesion strength.The wear rates of the coatings were investigated by ball-on-disc experiments at room temperature, 200 °C, 400 °C and 600 °C, using alumina balls as counter surfaces. At room temperature, the films show wear rates of the same order of magnitude of TiN and TiAlN coatings. On the other hand, the wear rates of solid solution (Ti,Al,Si)N coatings measured at 200, and 400 °C are one order of magnitude smaller than those measured at room temperature due to the formation of oxide-containing tribofilms on the wear tracks. At 600 °C the wear rates increase but still keep smaller than those measured at room temperature, although this effect can be influenced by the softening of the steel substrates by over-tempering. EDS analyses revealed that, between 200 °C and 400 °C, the oxidation of the coating occurs only at the contact zone between the film and the counterpart body due to the sliding process. 相似文献
8.
Three PVD nitride coatings (TiN, Ti55Al45N, and Ti35Al65N) with different Al content were deposited on the cemented carbides by cathode arc-evaporation technique. Microstructural and fundamental properties of these nitride coatings were examined. The friction and wear behavior of these coatings were evaluated at temperatures up to 600 °C. The wear surface features of the test samples were examined by scanning electron microscopy. Results showed that the friction coefficient of these nitride coatings is different depending on the temperature. The friction coefficient of TiN coating increased with the increase of test temperature; while the friction coefficient of Ti55Al45N and Ti35Al65N coatings with the addition of Al decreased with the increase of test temperature. The Ti55Al45N and Ti35Al65N coatings exhibited higher wear resistance over the one without Al (TiN coating). The wear resistance of these nitride coatings at high temperature wear tests is significantly dependent on their tribological oxidation behavior. The Ti55Al45N and Ti35Al65N coatings with the addition of Al exhibited improved wear resistance as compared to the TiN coating, which was attributed to that their tribo-chemically formed Al2O3 exhibited better tribological properties than the TiO2 of the latter. 相似文献
9.
The Ti(Y)N coatings were successfully deposited onto 18-8 stainless steel substrates by the hollow cathode discharge ion-plating method. The influence of the rare-earth element yttrium on the TiN coating properties was studied. The results show that the adhesion of the coating to the substrate were evidently enhanced by adding a small amount (0.2 wt.%) of the rare-earth element yttrium, showing a critical load of about 390 g which is much higher than that (230 g) of the TiN coating/substrate. Investigation on the corrosion resistance of the Ti(Y)N coating and the TiN coating was performed in 0.5 N Na2SO4 + 0.1 N H2SO4 + 0.1 N NaCl corrosion media by means of an electrochemical potentiodynamic polarization. The Ti(Y)N coating exhibited much better corrosion resistance than the TiN coating, whose passivity maintaining current is about one order in magnitude smaller than that of the TiN coating.The Ti(Y)N coatings deposited on some HSS-based tools were presented and compared with the TiN coating. The service lifetime of Ti(Y)N coated tools is approximately 36% higher (on the pinion shape cutters) and about 50% higher (on punch side pin) compared to that of TiN coated. The Ti(Y)N coatings showed such excellent performance. It is attributed to that the transition area of Ti(Y)N/substrate consisted of three sublayers which revealed a gradual change of phase structure and composition, so that the adhesion of the coating/substrate was evidently enhanced. Moreover, Ti(Y)N coating showed a preferred orientation with (111) plane which is favorable to improve wear resistance and corrosion resistance of the coating. 相似文献
10.
J.L. Endrino G.S. Fox-Rabinovich W. Kalss L. Soriano A. Gutiérrez 《Surface & coatings technology》2009,204(3):256-262
In this study, cemented carbide ball nose end mills with nano-crystalline Al0.67Ti0.33N hard PVD coatings deposited by cathodic arc evaporation were annealed at 700 °C during 2 h in a controlled atmosphere environment (argon + oxygen mixture) and in vacuum. The changes of structure and properties of the treated coating surfaces have been analyzed using both cross-sectional scanning electron microscopy (SEM) and x-ray absorption spectroscopy (XAS) of the N-K and O-K edges. Cutting tools have been run through ball nose end milling of hardened H13 steel (HRC 50) where temperature or stress dominating phenomena control tool life. The data obtained indicate that an AlTiN coated cutting tool can be modified upon annealing at low temperature conditions and should be considered as a composite surface engineered material. It is shown that increased tool life could be achieved if annealing of AlTiN is performed in an oxygen-containing atmosphere. A variety of different characteristics should be optimized to achieve better wear resistance of the cutting tools with annealed Al0.67Ti0.33N coating under high temperature and stress cutting conditions. 相似文献
11.
I. Endler M. Höhn H. Holzschuh S. Ruppi H. Westphal 《Surface & coatings technology》2010,205(5):1307-1312
Ti1 − xAlxN is a well established material for cutting tool applications exhibiting a high hardness and an excellent oxidation resistance. A main route for increasing the performance of Ti1 − xAlxN is the incorporation of further elements. Therefore the main objective of this work is to improve the properties and wear resistance of aluminum-rich CVD-TiAlN coatings by incorporating carbon. A new Low Pressure CVD process was employed for the deposition of a very aluminum-rich TiAlCN layers. The process works with a gas mixture of TiCl4, AlCl3, NH3, H2, N2, Ar and ethylene as carbon source. In this work microstructure, composition, properties and cutting performance of CVD-TiAlCN coatings were investigated.Hard aluminum-rich TiAlCN coatings were obtained at 800 °C and 850 °C consisting of a composite of fcc-Ti1 − xAlxN and minor phases of TiN, h-AlN and amorphous carbon. WDX analysis indicates only a low carbon content < 2 at.%. Lattice constant calculations suggest that carbon atoms should not be incorporated in the Ti1 − xAlxN lattice. From TEM analysis and Raman spectroscopy it is evident that carbon is mainly located at the grain boundaries as a-C phase. Therefore these fcc-Ti1 − xAlxN(C) coatings with low carbon content are rather a composite of fcc-Ti1 − xAlxN and an amorphous carbon phase (a-C). At 900 °C the metastable fcc-Ti1 − xAlxN nearly disappears and co-deposition of TiN and h-AlN occurs. The layers deposited at 800 °C and 850 °C possess a high hardness around 3000 HV and compressive stress. CVD-TiAlCN coatings prepared at 850 °C shows also an amazing thermal stability under high vacuum conditions up to 1200 °C. Aluminum-rich composites fcc-Ti1 − xAlxN/a-C with x > 0.8 exhibit a superior cutting performance in different milling tests. 相似文献
12.
For the development and introduction of new coated cutting tools (i.e. new combinations of cutting materials and hard coatings), it is necessary to carry out a number of studies with the purpose of optimizing the coatings composition and processing procedures, and also to test new tools under working conditions. The aim of this paper is to establish a common model for environmentally oriented quality management in the use and development of coated ceramic cutting tools with new coating systems. The paper also presents an investigation of the results of tribological and cutting properties of the coatings deposited with the PVD and CVD techniques on cutting inserts made from (Al2O3 + TiC) tool ceramics. Tests were carried out on ceramic inserts, uncoated and PVD or CVD-coated, with gradient, mono-, multi- (nano) layers and multicomponent hard wear resistant coatings composed of TiN, Ti(C, N), (Ti, Al)N, (Ti, AlSi)N and Al2O3 layers. 相似文献
13.
E.K. Tentardini C. Kwietniewski E. Blando I.J.R. Baumvol 《Surface & coatings technology》2009,203(9):1176-1181
Non-isostructural Ti0.7Al0.3N(cubic B1)/Ti0.3Al0.7N(hexagonal B4) nanoscale multilayers were deposited by dc magnetron sputtering on steel substrates, with nominal periods of 6, 10, 20 and 40 nm. The structure, composition, periodicity, and interface abruptness of the samples were characterized by X-ray diffraction, glow discharge optical spectroscopy, medium energy ion scattering, and narrow resonant nuclear reaction profiling. The nanohardness and elastic modulus of the samples were determined, revealing superhardness of up to 57 GPa for the lowest nanoscale multilayer period. The H3/E2 ratios were found to be superior to those of most metal nitride multilayers commonly used as protective coatings, which indicates a superior wear resistance for the present nanostructured coating. The results are discussed in terms of the present stage of understanding of nanoscale multilayer effects on the tribological properties of protective coatings. 相似文献
14.
B.D. Beake J.F. Smith G.S. Fox-Rabinovich J.L. Endrino 《Surface & coatings technology》2007,201(8):4585-4593
A novel laboratory technique, nano-impact testing, has been used to test Ti1−xAlxN (x = 0.5 and 0.67) PVD coated WC-Co inserts at 25-500 °C. Cutting tool life was studied under conditions of face milling of the structural AISI 1040 steel; the end milling of hardened 4340 steel (HRC 40) and TiAl6V4 alloy. A correlation was found between the results of the rapid nano-impact test and milling tests. When x = 0.67 improved resistance to fracture was found during milling operations and also in the nano-impact test of this coating compared to when x = 0.50. The coating protects the cutting tool surface against the chipping that is typical for cutting operations with intensive adhesive interaction with workpiece materials such as machining of Ti-based alloys. The results give encouragement that the elevated temperature nano-impact test can be used to predict the wear and fracture resistance of hard coatings during milling operations. At 500 °C nanoindentation shows there is a lower H/Er ratio for the PVD coatings compared to room temperature, consistent with reduced fracture observed at this temperature in the nano-impact test. 相似文献
15.
T. Weirather A. Fian B. Sartory D. Caliskanoglu W. Kölker C. Mitterer 《Surface & coatings technology》2012
Recently, carbide-free alloying systems with yield strength Rp0.1 of up to 4000 MPa 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. 相似文献
16.
Al2O3 and Ti-6Al-4V alloy were brazed using Cu + TiB2 composite filler, which manufactured by mechanical milling of Cu and TiB2 powders. Typical interface microstructure of joint was Al2O3/Ti4(Cu,Al)2O/Ti2Cu + Ti3Al + Ti2(Cu,Al)/Ti2(Cu,Al) + AlCu2Ti/Ti2Cu + AlCu2Ti + Ti3Al + Ti2(Cu,Al) + TiB/Ti(s.s) + Ti2Cu/Ti-6Al-4V alloy. Based on temperature- and time-dependent compositional change, the formation of intermetallics in joint was basically divided into four stages: formation of interfacial Ti4(Cu,Al)2O in Al2O3 side, formation of Ti2Cu, Ti3Al, TiB, Ti2Cu, and AlCu2Ti in layers II and IV, formation of Ti2(Cu,Al) and AlCu2Ti in layer III, formation of Ti + Ti2Cu hypereutectoid organization adjacent to Ti-6Al-4V alloy. TiB in situ synthesized in joint not only acted as low thermal expansion coefficient reinforcement to improve the mechanical properties at room temperature, but also as skeleton ceramic of joint to increase high temperature mechanical properties of Al2O3/Ti-6Al-4V alloy joint increasing. When the joint containing 30 vol.% TiB brazed at 930 °C and 10 min of holding time, the maximum room temperature shear strength of joint was 96.76 MPa, and the high temperature shear strength of joint was 115.16 MPa at 800 °C. 相似文献
17.
Metastable Ti–Al–N and Cr–Al–N coatings have been proven to be an effective wear protection due to their outstanding mechanical and thermal properties. Here, a comparative investigation of mechanical and thermal properties, for Ti–Al–N and Cr–Al–N coatings deposited by cathodic arc evaporation with the compositions (c-Ti0.52Al0.48N, c/w-Ti0.34Al0.66N and c-Cr0.32Al0.68N) widely used in industry, has been performed in detail. The hardness of Ti0.52Al0.48N and Ti0.34Al0.66N coatings during thermal annealing, after initially increasing to the maximum value of ~ 34.1 and 38.7 GPa with Ta up to 900 °C due to the precipitation of cubic Al-rich and Ti-rich domains, decreases with further elevated Ta, as the formation of w-AlN and coarsening of precipitated phases. A transformation to Cr2N and finally Cr via N-loss in addition to w-AlN formation during annealing of the Cr0.32Al0.68N coating occurs, and thus results in a continuous decrease in hardness. Among our coatings, the mixed cubic-wurtzite Ti0.34Al0.66N coating exhibits the highest thermal hardness, but the worst oxidation resistance. The Cr0.32Al0.68N coating shows the best oxidation resistance due to the formation of dense protective α-Al2O3-rich and Cr2O3-rich layers, with only ~ 1.4 μm oxide scale thickness, after thermal exposure for 10 h at 1050 °C in ambient air, whereas Ti–Al–N coatings are already completely oxidized at 950 °C. 相似文献
18.
Jianing LiChuanzhong Chen Zhaoqing LinTiziano Squartini 《Journal of Alloys and Compounds》2011,509(14):4882-4886
Laser cladding of the Fe3Al + TiB2/Al2O3 pre-placed alloy powder on Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiB2/Al2O3 ceramic layer, which can greatly increase wear resistance of titanium alloy. In this study, the Ti3Al/Fe3Al + TiB2/Al2O3 ceramic layer has been researched by means of electron probe, X-ray diffraction, scanning electron microscope and micro-analyzer. In cladding process, Al2O3 can react with TiB2 leading to formation of amount of Ti3Al and B. This principle can be used to improve the Fe3Al + TiB2 laser cladded coating, it was found that with addition of Al2O3, the microstructure performance and micro-hardness of the coating was obviously improved due to the action of the Al-Ti-B system and hard phases. 相似文献
19.
20.
a-CNx/TiN multilayer films were deposited onto high-speed steel substrates by pulsed laser ablation of graphite and Ti target alternately in nitrogen gas. The composition, morphology and microstructure of the films were characterized by energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The tribological properties of the films in humid air were investigated using a ball-on-disk tribometer. The multilayer films consist of crystalline TiN, metallic Ti and amorphous CNx (a-CNx). With an increase in thickness ratio of CNx to bilayer, the hardness of multilayer film decreases, friction coefficient decreases from 0.26 to 0.135, and wear rate increases. The film with thickness ratio of CNx to bilayer of 0.47 exhibits a maximum hardness of 30 GPa and excellent wear rate of 2.5 × 10− 7 mm3 N− 1 m− 1. The formation of tribo-layer was observed at contact area of Si3N4 ball. The film undergoes the combined wear mechanism of abrasion wear and adhesion wear. 相似文献