M2 Steel Substrates Research Articles

Study on adhesion and wear resistance of multi-element (AlCrTaTiZr)N coatings

Multi-element (AlCrTaTiZr)N films were deposited on cemented carbide and M2 steel substrates by reactive RF magnetron sputtering. Prior to nitride film deposition, an interlayer between the film and the substrate was introduced to improve adhesion property. The influence of interlayer materials (Ti, Cr, and AlCrTaTiZr alloy) and interlayer thickness (0–400 nm) on the adhesion and tribological properties of films was investigated. In this study, the nitride film deposited at R N = 20% exhibited the highest hardness (35.2 GPa) and the lowest residual compressive stress (− 1.52 GPa), and was prepared as the top layer for further testing. The interlayer materials can effectively improved the film adhesion onto the cemented carbide substrates, and the adhesive failure was not observed even under the normal load of 100 N. For M2 steel substrates, only the Cr interlayer can slightly improve the film adhesion, and the cohesive and adhesive failure can be found at relatively lower applied load. The optimal interlayer thickness was 100–200 nm for the 1 µm-thick (AlCrTaTiZr)N film and can be related to the stress evolution. The friction coefficient and wear rate for the (AlCrTaTiZr)N film were 0.82 and 4.9 × 10 − 6 mm 3/Nm, respectively, and almost kept constant under different interlayer materials and thickness. The worn-through event of the nitride film during tribological test occurred easily owing to its poor adhesion behavior, and can be improved by interlayer additions.

Microstructural and chemical characterisation techniques for nanostructured and amorphous coatings

A full characterization of amorphous or nanostructured coatings at the microstructural level has some intrinsic difficulties associated with the lack of long range order and reference compounds, which often make difficult their study. Only by the combination of different characterization techniques is possible in many cases to achieve valuable chemical and structural information. In this paper, three different systems were used to illustrate how the combination of characterization techniques, as TEM associated to ED or EELS, EFTEM, SEM, XPS, RBS and XRD was determinant to correlate microstructure with deposition parameters and properties in such complex systems. The coatings were deposited on silicon and AISI M2 steel substrates by magnetron sputtering under different Ar/N2 gas mixtures from Ti and C targets (system 1 and 2) or a Si target (system 3). In each case, the performed characterization allowed to get a deeper understanding of the whole system and explain their mechanical response. The studied systems are: (i) Ti-TiN-CNx multilayered coatings: the chemical and structural analysis shows that a gradual enrichment in nitrogen and nitride phases from the metallic substrate to the CNx top layer is responsible for the improvement of the adhesion properties. (ii) Ti-C-N: the existence of a nanocrystalline TiC phase embedded in an amorphous carbon matrix is demonstrated by the microstructural and chemical analysis for samples prepared under pure Ar. When N2 is introduced in the gas phase, the nanocrystalline structure is not seen and the chemical composition is enriched in amorphous non-stoichiometric CNx. (iii) SiOxNy: although the coatings present similar composition, small differences in microstructure are observed, which can be responsible for different mechanical properties.

Microstructure, Hardness and Corrosion Resistance of ZrN Films Prepared by Inductively Coupled Plasma Enhanced RF Magnetron Sputtering

ZrN films were deposited on Si(111) and M2 steel by inductively coupled plasma (ICP)-enhanced RF magnetron sputtering. The effect of ICP power on the microstructure, mechanical properties and corrosion resistance of ZrN films was investigated. When the ICP power is below 300 W, the ZrN films show a columnar structure. With the increase of ICP power, the texture coefficient (Tc) of the (111) plane, the nanohardness and elastic modulus of the films increase and reach the maximum at a power of 300 W. As the ICP Power exceeds 300 W, the films exhibit a ZrN and ZrNx mixed crystal structure without columnar grain while the nanohardness and elastic modulus of the films decrease. All the ZrN coated samples show a higher corrosion resistance than that of the bare M2 steel substrate in 3.5% NaCl electrolyte. The nanohardness and elastic modulus mostly depend on the crystalline structure and Tc of ZrN(111).

Enhancing the hardness of arc-ion-plated nanocrystallite TiN films

Enhancing the hardness of nanocrystallite TiN films synthesized on M2steel substrate in a vacuum cathode multi-arc ion-plating system wasinvestigated. The synthesized film gives: (i) mean grain sizes of about 12.7 nm forTiN111, 19.7 nmfor TiN200 and9.6 nm for TiN220; and (ii) achievable microhardness up to 45 GPa that is more than twice the 22 GPa forstandard TiN film. Such hardness enhancement is anticipated as being mainly due to:(i) the formation of nanoscale crystalline grains; (ii) the preferential orientation and growthof grains in the close-packed plane (111); and (iii) induced residual stress within the film byion bombardment.

Study of the Si Chemical Bonding and the Semiconductive Behavior of SiCN Coatings and their Correlation with Anti‐Corrosion Properties

AbstractAmorphous hydrogenated SiCN coatings have been deposited by a PACVD process on M2 steel and silicon substrates. The nitrogen content within the coatings was varied by changing the synthesis conditions. The chemical composition and nature of bonding have been studied by XPS and by X‐ray‐induced AES. The electrochemical and the semi‐conductive properties were evaluated by polarization curves and by using the Mott‐Schottky experiments, respectively. When increasing the N/Si ratio, we observed an increase of Si atoms inside the film structure, which were directly bonded to nitrogen. This gradual incorporation of N modified the electrochemical behavior of the films displaying a variation of the density of charge carriers and the semiconductive behavior (p‐ to n‐type). The modified Auger parameter of silicon was used to determine the nature of the silicon chemical bonding inside the [SiCN]‐based coatings and to predict their corrosion behavior.magnified image

Effect of tribological media on tribological properties of multilayer Cr(N)/C(DLC) coatings

In this research, Cr(N)/C(DLC) multilayered coatings were deposited on M2 steel substrates by an unbalanced magnetron sputtering technique. By varying the substrate rotation speed, four multilayered coatings with different bilayer thickness were produced. The bilayer thickness and structure of multilayered coatings were characterized by low-angle XRD, XPS depth profile, and cross-section TEM observation. The tribological investigation focused on the effect of layer thickness and tribological media on tribological property of the multilayer coatings against Al counterface. A pin-on-disc tribometer with a tribological medium container was used to investigate the wear behaviours of the four multilayered coatings under dry and wet (distilled water and S500 coolant) sliding. A stylus surface profilometer was used to measure wear rate. The investigation of wear tracks and wear mechanism was performed using Scanning Electron Microscopy (SEM). The research results showed that coatings with different bilayer period performed different tribological behaviour. The proper tribological media applied in the wear tests could improve the wear properties of multilayer coatings.

Use of silane for the deposition of hard and oxidation resistant Ti–Si–N coatings by a hybrid cathodic arc and chemical vapour process

Ti–Si–N coatings were deposited on M2 steel substrates using a hybrid cathodic arc and chemical vapour deposition process. Silane was used as the silicon precursor. Whatever the films silicon content, only TiN grains were detected by X-ray diffraction. The mean grain size was estimated to be lower than 10 nm. The silicon content strongly influenced the TiN preferred orientation. Depth sensing indentation showed that films with Si/Ti = 0.08 exhibited a hardness close to 43 GPa. Silicon addition into TiN-based coatings induced an improvement of their oxidation resistance. The film properties were comparable to those obtained for Ti–Si–N coatings deposited using a Ti–Si target, indicating that the hybrid process was suitable for the deposition of hard and oxidation resistant Ti–Si–N coatings.

Tribological properties of a-C/Cr(N) coatings in micro-and nano-scales

This research was involved with comparison study of tribological properties of a-C/Cr(N) multilayered coatings in micro-and nano-scales. The a-C/Cr(N) coatings were deposited on Si wafers and M2 steel substrates by unbalanced magnetron sputtering of one Cr and two C targets. Cross-section TEM analysis was used to determine the layer periodicity of the coatings. Nanoindentation was used to measure hardness ( H) and elastic modulus ( E), and also perform nanowear tests. Pin-on-disc tribological tests were conducted to evaluate tribological properties of the coatings in micro-scales. H / E, H 3 / E 2, and h f / h max values were calculated for predication of wear performance of the coatings. It was found that the ranking of coating wear resistance was consistent to the order of H / E, H 3 / E 2, and h f / h max values. The coating with a periodicity of 4 nm had the highest hardness and the best wear resistance in both nano-and micro-scales.

Microstructure, adhesion and tribological properties of W–C:H x% coatings deposited on M2 and WC substrates

W–C:H x% coatings with slightly different hydrogen contents are deposited on AISI M2 steel and WC substrates using an unbalanced magnetron (UBM) sputtering process. The microstructure, adhesion and tribological properties of the W–C:H x% coatings are found to vary with the hydrogen content. For a hydrogen content of more than 1.2 at.%, the microstructure of the W–C:H x% coating changes from a columnar form to a featureless morphology. The adhesion of the coatings deposited on the WC substrates is significantly better than that of the coatings deposited on the M2 substrates. Of the various coatings, the W–C:H 1.3% coating provides the best tribological properties, including the lowest wear depth and the lowest friction coefficient.

The structure and hardness of magnetron sputtered Ti–Al–N thin films with low N contents (< 42 at.%)

Thin films of Ti–Al–N were deposited by d.c. magnetron sputtering on M2 (AISI) steel substrates. Two targets configurations were used: pure targets of Ti and Al placed at 90° and two facing targets of titanium encrusted with aluminium rods (composite targets). The nitrogen flow was varied from 0 to 12 sccm. The N/(N + Ti + Al) and Al/(Al + Ti) atomic ratios in the films ranged from 0% to 41.9% and 24% to 28.6%, respectively. The deposition rate was almost two times higher for the films deposited from composite targets. Both the deposition rate and the aluminium content started to decrease at 6 sccm for the films deposited from pure targets and only at 12 sccm for the films deposited from composite targets. For both target configurations, polycrystalline α-Ti was deposited at low N contents and, as more nitrogen was added, a progressive loss of crystallinity was observed until amorphous films are deposited. Ti(Al)N was deposited from pure targets at the highest nitrogen content. The hardness of the films deposited from composite targets smoothly increases from 12.5 to 27 GPa with increasing nitrogen. Within the α-Ti nitrogen deposition range, the hardness of the films deposited from pure targets slowly increases from 15 to 17.5 GPa while much higher hardness values were measured for the amorphous and the Ti(Al)N film (36 and 34.5 GPa, respectively).

Characterisation of Pristine and Recoated electron beam evaporation plasma-assisted physical vapour deposition Cr–N coatings on AISI M2 steel and WC–Co substrates

This paper is focussed on the characterisation of electron beam evaporation plasma-assisted physical vapour deposition Cr–N coatings deposited on AISI M2 steel and hardmetal (K10) substrates in two different conditions: Pristine (i.e., coated) and Recoated (i.e., stripped and recoated). Analytical methods, including X-ray diffraction (XRD), scanning electron microscopy, scratch adhesion and pin-on-disc tests were used to evaluate several coating properties. XRD analyses indicated that both Pristine and Recoated coatings consisted of a mixture of hexagonal Cr 2N and cubic CrN, regardless of substrate type. For the M2 steel substrate, only small differences were found in terms of coating phases, microstructure, adhesion, friction and wear coefficients between Pristine and Recoated. Recoated on WC–Co (K10) exhibited a less dense microstructure and significant inferior adhesion compared to Pristine on WC–Co (K10). The wear coefficient of Recoated on WC–Co was 100 times higher than those exhibited by all other specimens. The results obtained confirm that the stripping process did not adversely affect the Cr–N properties when this coating was deposited onto M2 steel substrates, but it is clear from the unsatisfactory tribological performance of Recoated on WC–Co that the stripping process is unsuitable for hardmetal substrates.

Mechanical and tribological properties of Cr–N and Cr–SI–N coatings reactively sputter deposited

Cr–N and Cr–Si–N coatings have been deposited with two nitrogen flow rates, 6 and 10 sccm, for a constant argon flow rate of 20 sccm with various amounts of silicon, in an ALCATEL SCM 650 sputtering system. DC and pulsed DC were used to power the target and the silicon coupons, placed in the erosion track, whereas the substrate holder was RF biased. All the deposited coatings are dense and well bonded to the M2 steel substrates. At 10 sccm N2, the increase of the silicon content up to 2.5 at.% into the coating leads to a maximum hardness (H) and a low Young's modulus (E). A further increase of the Si content yields to both the decrease of H and E. At 6 sccm N2, a similar but less pronounced phenomena are observed.Ball on disk tests under a normal load of 5 N applied to a 100Cr6 ball were performed to investigate the wear resistance of the coatings. Cr–Si–N coatings showed low friction coefficients and no measurable wear after 500 m of sliding at 0.2 m s−1.

Structure and mechanical properties of Ti–Al films deposited by magnetron sputtering

Thin films of Ti–Al were deposited by d.c. magnetron sputtering on M2 (AISI) steel substrates. A composition scan of the Ti–Al system was carried out using pure Ti and Al targets placed at 90°. X-ray diffraction showed that for the high Al content films (71.5–86.1 at.% of Al) only the face centred cubic (f.c.c.) Al phase was deposited with a (111) preferential orientation. Within this range of compositions, both the width of the (111) planes diffraction peaks and the hardness of the films increased (from 8.9–13 GPa) with increasing Ti content. The Ti–Al films deposited with aluminium contents in the range from 32.5 to 57.1 Al at.% showed low hardness (8.8–10.3 GPa) and only a broad diffraction peak centred at 2θ≈45.4° was detected. For the high titanium content films (3.7–19.9 at.% of Al) the hexagonal close packed (h.c.p.) Ti phase peaks were detected by X-ray diffraction, superimposed on a broad diffraction peak centred at 2θ≈44.8°. These films showed the highest hardness values (up to 23 GPa). The composition range from 19.9 to 32.5 at.% of Al was selected for further work since it includes the films that presented the best combination between hardness and friction coefficient.

Tribological and dry machining evaluation of superhard TiB 2/TiC multilayer coatings deposited on Si(001), M2 steel, and C3 WC cutting tool inserts using magnetron sputtering

TiB 2/TiC multilayer coatings were synthesized in a dual-cathode unbalanced magnetron sputter–deposition system with substrate rotation. Our previous research has demonstrated that all coatings on M2 steel are polycrystalline with TiB 2(001) preferred orientation and have a layer structure. Compressive stress in these coatings is less than 2 GPa, with hardness up to 60 GPa, which corresponds to 100% hardness enhancement over the rule-of-mixture value. This paper concentrates on the tribological and dry machining evaluation of these coatings. Coatings were deposited on Si(001), polished M2 steel, and C3 WC cutting tool inserts. From dry block-on-ring tribotesting, the 3:0.5 multilayer (i.e., the layer thickness is 3.0 nm for TiB 2 and 0.5 nm for TiC) coating provides four times improvement in wear resistance over the uncoated M2 steel substrate. In addition, dry machining was performed using AISI 1018 steel and 319 aluminum alloy cylindrical workpieces. Monolithic TiB 2 and 3:1 multilayer coatings (i.e., the layer thickness is 3.0 nm for TiB 2 and 1.0 nm for TiC) have the best performance: the flank wear was reduced by about a factor of ten compared with the uncoated tool after a cutting distance of 600 m. Results from cutting force measurements demonstrate that as far as dry machining is concerned, there is no direct correlation among cutting forces, room-temperature hardness, and flank wear. In dry machining of aluminum, the carbide tool deposited with the 3:1 multilayer, unlike other tools, has negligible buildup on the rake face. This results in better and more consistent surface finish of the final workpiece and less likelihood for premature tool breakage.

Nanometric chromium nitride/chromium carbide multilayers by r.f. magnetron sputtering

Chromium nitride/chromium carbide (CrN/CrC) multilayers, with periods between 5 and 100 nm, were deposited on M2 steel and silicon substrates using a single cathode r.f. magnetron sputtering system. The target was pure chromium (99.99%) and the nitride/carbide multilayer structure was obtained in a continuous process by alternating the sputtering gas composition between Ar/N 2 and Ar/CH 4 reactive mixtures. The deposition parameters were arranged to obtain optimized properties for both materials in individual coatings and then implemented in multilayered film deposition. X-Ray diffraction allowed for a detailed characterization of the different phases obtained in both CrN and CrC individual coatings and in CrN/CrC multilayers. The periodic structure of the multilayers was characterized using low-angle X-ray diffraction and transmission electron microscopy. The mechanical and tribological properties such as hardness, residual stress, sliding wear behavior and friction coefficient in multilayers were analyzed by means of nanoindentation and ball-on-disk techniques and their dependence on period thickness are presented. These properties of the CrN/CrC multilayers are compared with those of CrN and CrC individual coatings.

Microstructural characterization of Ti–TiN/CN x gradient-multilayered coatings

A good mechanical performance of carbon nitride (CN x )-based hard coatings grown onto steel components requires an optimal adhesion to the substrates. In the present work, the CN x films have been joined to the AISI M2 steel substrates through a Ti–TiN functionally gradient underlayer. Three types of Ti–TiN/CN x graded systems were deposited by means of magnetron sputtering technique in different growing conditions and the adhesion properties were evaluated by scratch tests. Chemical and structural characterization at the nanoscale for these systems were carried out by grazing incidence X-ray diffraction, transmission electron microscopy (TEM), energy dispersive X-ray analysis, energy filtered TEM and electron energy loss spectroscopy. This complete microcharacterization of the multilayered Ti–TiN/CN x systems coupled with the observed adhesion properties has allowed to identify relationships between the deposition conditions and the material chemistry and structure, in order to reach the desired coating performance. A gradual enrichment in nitrogen and nitride phases was detected from the metallic substrate to the CN x top layer affording higher critical load for delamination.

Structure and wear resistance of tetrahedral amorphous carbon films

High quality tetrahedral amorphous carbon films (ta-C) have been prepared on silicon and M2 steel substrate by filtered cathodic vacuum arc deposition. The structures, mechanical properties, adhesion and wear resistance of the tetrahedral amorphous carbon films have been investigated. The hardness and elastic modulus of the tetrahedral amorphous carbon films are determined by nano-indentation tests. The results show that the hardness and elastic modulus of the tetrahedral amorphous carbon films are 79 and 431 GPa, respectively. The friction performance of the tetrahedral amorphous carbon films was also studied. The coefficient of tetrahedral amorphous carbon film on substrate of M2 steel is 0.20, and stable up to 2500 cycles and the wear rate of tetrahedral amorphous carbon film is 1.233 × 10 −8 mm 3/N m for an applied load of 5 N and 2500 cycles.

Influence of Al(Er) interlayer on the mechanical properties of AlN(Er) coatings

AlN(Er) thin films were deposited by sputtering on M2 steel (AISI) and Si substrates with different thickness of an Al(Er) interlayer. No significant variations were observed in the chemical composition and structure of the AlN(Er) films. The films in all cases presented excess nitrogen in relation to AlN stoichiometry. The diffraction peaks were strongly shifted to lower angles due to the presence of Er. The hardness of the films is approximately 32 GPa and does not change with the thickness of the Al(Er) interlayer. The cohesion and adhesion of the AlN(Er) films were improved with the inclusion of the Al(Er) interlayer; the cohesive and adhesive critical load values increased from 7 and 17 N to 15 and 27 N, respectively.

Microstructure and adhesion characteristics of diamond-like carbon films deposited on steel substrates

For tribological applications, the low friction coefficient and high microhardness of diamond-like carbon (DLC) films give significant advantages in cutting and forming non-ferrous materials. The inherently large residual stress of DLC films, however, prevents the depositing of thicker films. This study designed and implemented a compound interface, comprising a series of metal, metal nitride, and metal carbonitride interlayers deposited in a graded structure, between the DLC (a metal-doped a-C:H) film and M2 steel substrates. The tribological performance of the interface was evaluated using a scratch tester and ball-on-disk tribometer. Meanwhile, the failure mechanism of DLC deposited on M2 steel substrates was examined using SEM/EDS and TEM microscopy. Experimental results demonstrate an improved DLC hard coating with superior adhesion strength on the steel substrates.

The influence of Er doping of Al–N sputtered coatings on their mechanical properties

Thin films of AlN(Er) were deposited on M2 steel substrates using r.f. reactive magnetron sputtering starting from an aluminium target in Ar/N 2 mixtures. Er doping was achieved by partially covering the aluminium target with an adequate number of erbium pieces. All depositions were achieved with a discharge power of 600 W, P N2/ P tot=0.5 and a total pressure of 0.74 Pa. The Al/(N+Al) ratio in the as-deposited films varied between 0.48 and 0.51 while Erbium contents ranging from 0.2 to 3.5 at.% were achieved. X-ray diffraction showed that the AlN(Er) films with Erbium contents up to 1.4 at.% have a crystalline structure with a preferential orientation on the (002) planes. However, as a consequence of lattice distortion and/or defect generation originated by the incorporation of Er atoms in the AlN structure, the films became amorphous for higher Er contents. The highest hardness values were obtained for the crystalline AlN(Er) films (up to 31 GPa at 1.2 at.% of Er) while a significant decrease of the hardness was observed when the films became amorphous (22.5 GPa at 3.5 at.%). The mean critical loads for cohesive failure measured by scratch test were quite similar for all the coatings (varying from 7 to 8 N) revealing the brittle character of the deposited films. The mean critical loads for adhesive failure were in the range of 12 N for low Er content to 22 N for the higher Er content. Concerning the possible use of AlN(Er) films in tools applications, these films have a suitable hardness but a poor adhesion to steel alloys when compared with layers usually used for mechanical protection.