Closed-field Unbalanced Magnetron Sputtering Ion Research Articles

Microstructure and High-Temperature Friction and Wear Properties of CrAlMoN Film

Closed-field unbalanced magnetron sputtering ion plating was used to form CrAlMoN films on the surface of single-crystal silicon and tool steel. The composition and morphology of the films were determined through energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. High-temperature friction and wear properties of CrAlMoN films were assed using a friction and wear tester and by studying the film cross-sections. The hardness of CrAlMoN films was determined using a nanoindenter. Results showed that CrAlMoN films have a nanomultilayer structure, with the same fcc structure as CrN. At room temperature, the hardness and wear resistance of CrAlMoN films are greater than that of CrAlN films. The friction properties of CrAlMoN films varied widely with an increase in the temperature. At 600 °C, the friction performance of CrAlMoN films degrades rapidly, and the degree of film wear is significantly increased. In contrast, CrAlN films retain high wear resistance at 600 °C.

Harmonizing mechanical responses of nanostructured CrN coatings via Ni additions

CrN coatings are often brittle and prone to abrupt failure. Incorporation of Ni is known to have significant effects on the chemical composition, microstructure and mechanical behaviour of chromium nitride coatings synthesised by PVD, and thus imparting toughness. In this study, a series of NiCrN coatings, with varying Ni concentrations, were deposited onto AISI M2 tool steel substrates through closed-field unbalanced magnetron sputtering ion plating (CFUMSIP). The phase compositions, microstructure, mechanical properties and deformation behaviour of the coatings were characterised by XRD, AFM, FIB, TEM/EDS and indentation testing. Residual stresses of these as-prepared coatings were measured by the XRD-sin2ψ method. A columnar structure was observed in all coatings, although grain refinement at higher NiCr target currents was noted. High hardness values of ~20 GPa were found in the coatings with the lower Ni (~5–14 at%) contents, associated with the effects of solid solution hardening, high compressive residual stress and grain refinement. Moreover, significant damage-tolerance, coupled with good hardness values (greater than ~12 GPa), was found in the NiCrN coatings deposited at INiCr ≥ 2 A. The presence of a metallic nickel-rich phase, together with nanoscale porosity, may contribute to stress dissipation and help maintain structural integrity.

Effect of Y content on the microstructure, tribological and corrosion properties of CrAlYN coatings deposited by magnetron sputtering

CrAlYN coatings with various Y contents (0.00 at%–2.67 at%) were deposited by closed-field unbalanced magnetron sputtering ion plating, and the effects of Y content on the microstructural, mechanical, and tribological properties of the CrAlYN coatings were investigated. The results showed that the synthesised CrAlYN coatings exhibited a face-centred cubic (fcc) structure. When the Y content increased to 2.67 at%, the preferential orientation of the CrAlYN coating changed from the (111) to the (200) plane. The hardness and Young’s modulus of the CrAlYN coatings first increased and then decreased with an increase in Y content; the highest values were 29.4 GPa and 390.6 GPa, respectively, at 1.13 at% Y. The wear properties of the CrAlYN coatings showed that the lowest wear rate and best wear resistance occurred at 1.13 at% Y. When the Y content was increased to 1.98 at%, the corrosion potential of the CrAlYN coating reached the maximum value of −0.4461 V, and the corrosion current decreased to 3.564 × 10−6 A cm−2. This CrAlYN coating exhibited the strongest corrosion resistance.

EFFECTS OF Mo CONTENT ON THE MICRO-STRUCTURE AND TRIBOLOGICAL PROPERTIES OF CrMoAlN FILMS

In recent decades, CrAlN coatings have been widely used for cutting tools due to their high hardness, good wear resistance, especially excellent thermal stability and oxidation resistance. However, the rapid development in high speeds and dry cutting applications demands further improvement in hardness and wear properties of CrAlN coatings. Mo nitrides coatings are commonly used as protective surface layers against wear and corrosion. The combination of CrAlN and Mo may lead to the development of new composite coatings with superior wear properties. In this study, the CrMoAlN multilayer coatings with different Mo contents were deposited on M2 tool steel and silicon wafers substrates by closedfield unbalanced magnetron sputtering ion plating (CFUMSIP) technique in a gas mixture of Ar+N2. The chemical composition, surface and cross sectional morphologies, microstructure, mechanical and tribological properties of coatings were studied by EDS, SEM, XRD, XPS, nano-indentation and pin-on-disk tribometer, respectively. The results indicate that the CrMoAlN coatings exhibit fcc structure. Mo atoms substitute Cr and/or Al atoms in CrAlN lattice forming the solid solution CrMoAlN coatings. The surface and cross-sectional morphologies of the CrMoAlN coatings show that the grain size and the column width decrease with the increasing of Mo content. Nano-indentation result reveals a promoted hardness and elastic modulus *浙江省自然科学基金资助项目Y15E050060 收到初稿日期: 2015-09-21,收到修改稿日期: 2016-03-09 作者简介:楼白杨,女, 1958年生,教授,博士 DOI: 10.11900/0412.1961.2015.00493 第727-733页 pp.727-733

Synthesis, characterisation and wear performance of W–Al coatings

W, W–15 at-%Al, W–30 at-%Al and W–45 at-%Al coatings were synthesised by using a reactive four-target DC closed field unbalanced magnetron-sputtering ion plating system. Structure, morphology, composition, hardness and adhesion were studied by using an X-ray diffractometer, an energy dispersive spectrometer, a scanning electron microscope, a scanning transmission electron microscope and nanohardness and scratching testers. Wear performance was evaluated by using a pin-on-disk wear tester. The sputtering deposition of this binary system led to the formation of single-layer W–Al coatings as a result of complete dissolution of the Al atoms into the W lattice during the depositing process. The W–15 at-%Al coating showed improved wear resistance as compared with the W coating.

Research on Microstructure and Tribological Properties of the Cp/AlSn Coatings Deposited by Magnetron Sputtering

The influences of microstructure and tribological properties of Cp/AlSn (Cp: carbon particule) composite films were applied to AlZn4.5Mg bearing alloy substrates using the closed-field unbalanced magnetron sputtering ion plating technique. The microstructure, phases and bond states of the coatings were separately characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The friction coefficients were measured using a pin-on-disc set-up. Results showed that the grain size and roughness of the films both decreased with increasing of carbon target current (IC) from 0.2 A to 0.8 A. Phases in the films were Al, Sn and C, although the films transformed from a crystalline state to amorphous when the carbon target current was applied. Al and Sn existed as pure metals. Carbon, composed of sp2and sp3bonds, mainly as sp2bonds, provided transfer films to reduce the friction coefficient of the films from 0.35 to 0.15. The specific wear ratio was a minimum, when the carbon target current was 0.4 A.

Effect of Ni addition on the structure and properties of Cr–Ni–N coatings deposited by closed-field unbalanced magnetron sputtering ion plating

Closed-field unbalanced magnetron sputtering ion plating (CFUMSIP) is a versatile technique for the preparation of high-quality coatings due to the enhancement of plasma density during deposition. In this study, Cr–Ni–N hard coatings with different Ni contents (0–64at.%) were deposited onto AISI M2 steel substrates by CFUMSIP in Ar–N2 reactive gas mixtures. The coatings were characterized in terms of their structure and properties by a variety of techniques, such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), micro-indentation, reciprocating wear tester, etc. The surface free energy of the coatings was calculated using the Owens–Wendt geometric mean approach. The experimental results indicated that the microstructure and properties of Cr–Ni–N coatings changed with the incorporation of Ni content at different level. The resultant Cr–Ni–N coatings were consisted of Cr2N, CrN and metallic Ni mixed phases. With the appropriate addition of Ni in the range of 20–40at.%, the fracture toughness and wear resistance could be improved as compared to the Cr–N binary coating, and the hardness remained relatively high (20–23GPa). Additionally, both low total surface energy (18–22mN/m) and low polar component of surface energy (0.1–0.2mN/m) could be obtained in the Cr–Ni–N coating system. Therefore, the Ni incorporation can provide an effective route to tailor the structure and properties of the Cr–Ni–N coatings. The good combined properties of the Cr–Ni–N coatings demonstrate their potential for applications in plastic injection molding.

Influence of Carbon Doping on Microstructure and Tribological Properties of CrN Coating

The influence of carbon doping on tribological properties of CrCN Coating was studied through preparation of coatings deposited on single crystal silicon and M2 high speed steel(HSS) substrate using closed-field unbalanced magnetron sputtering ion plating technique. The friction coefficients were measured by pin-on-disc set-up. The microstructure and bond states of the coatings were characterized by X-ray diffraxtion(XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). The results show that the friction coefficient of coating decreases from 0.75 to 0.38, the microhardness increases from 1930HV to 2302HV, and the specific wear ratio of the coatings decreases from 8.35110-5m3/Nm to 3.85910-5m3/Nm with the increasing of carbon target current(IC) from 0A to 1.5A. The analysis of microstructure shows that the coatings transform from crystalline state to amorphous state and the grain size of the coatings decreases with the increasing of carbon target current.

Development of Zr-Ti-N Coatings for Micro Drills for Machining of PCBs

A group of Zr-Ti-N coatings was prepared and studied to access their potential as a protective layer for micro drills to obtain cutting tool wear improvement. The coatings were grown using an industrial-scale four-target closed-field unbalanced magnetron sputtering ion plating system, employing one Ti and three Zr targets working in residual N2 atmosphere. To achieve Zr-Ti-N coatings with varying Ti doping content, the current applied to the Ti target was subjected to change from 0A to 3.6A while those to the Zr targets were kept constant. The coatings were characterized using GDOES, XRD, SEM, Vickers microhardness tester, scratch tester and Rockwell C indentation tester. Evaluation of wear improvement by Zr-Ti-N coatings for microdrills was conducted by machining of FR4 print circuit boards. It was found that the coatings with 16.5 at.% Ti doping content showed the highest microhardness and wear improvement for microdrills. Wear of microdrills with this coating could be reduced by a factor of two as compared with traditional TiN coated ones.

The effect of unbalanced coefficient of magnetron on the structure and properties of CN x coatings

The effect of unbalanced coefficient of magnetron (UCM) on the structure and tribological properties of CrNx hard coatings was studied. The CrNx coatings were deposited on both Si wafer and hardened tool steel substrates using a closed-field unbalanced magnetron sputtering ion plating technique in a gas mixture of Ar+N2 under different unbalanced magnetron conditions. The coatings were characterized by means of XRD, XPS, SEM, microhardness tester and pin-on-disc tribometer to study respectively their structure, chemical bonding state, microstructure, hardness and tribological properties. The experimental results show that the UCM has a profound effect on the structure, hardness and tribological properties of the CrNx coatings. With increasing the values of UCM, the dominant phases in the deposited coatings evolved from Cr+Cr2N to Cr2N+CrN, the microstructure became denser and the hardness increased; in addition, reduced coefficient of friction and improved wear resistance of CrNx coatings were also observed under a larger UCM.

Study on tribological property of CrCN coating based on magnetron sputtering plating technique

The influence of carbon doping on tribological properties of CrCN coating was studied through preparation of coatings deposited on single crystal silicon and M2 high-speed steel (HSS) substrate using closed-field unbalanced magnetron sputtering ion plating technique. The friction coefficients were measured by pin-on-disc set-up and the wear traces of the coatings were observed by optical microscope. The microstructure and bond states of the coatings were characterized by atomic force microscope (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that the friction coefficient of coating decreases from 0.75 to 0.38, the micro-hardness increases from 1930 HV to 2300 HV, and the specific wear ratio of the coatings decreases from 8.351 × 10 −15 m 3/Nm to 3.859 × 10 −15 m 3/Nm with the increasing of carbon target current ( I C ) from 0 A to 1.5 A. The grain size and the roughness of the coatings both decrease with the increasing of carbon target current, at the same time the coatings transform from crystalline state to amorphous state.

Design of functionally graded carbon coatings against contact damage

Three different functionally graded amorphous carbon (a-C) thin films were deposited on to aluminium substrates using a closed-field unbalanced magnetron sputtering ion plating method. The closed-field configuration prohibits the loss of secondary electrons and consequently enhances the plasma density significantly. The functional gradient of the a-C films was achieved by varying the bias voltage linearly during deposition. Three graded a-C systems possessing different variations in Young's modulus were deposited with the highest Young's modulus at the (i) top surface, (ii) interface or (iii) middle of the film. Of the three systems investigated, the one with the highest Young's modulus at the middle of the film thickness was found to exhibit significantly lower levels of cracking at higher indentation depths. Finite element models that included an embedded ring crack controlled by cohesive zone elements were developed to clarify the effect of ring cracks on the deformation of the films. This study provides guidance for the design of functionally graded coatings against contact damage.

Microstructure and Mechanical Properties of Multilayer Ti(C, N) Films by Closed-field Unbalanced Magnetron Sputtering Ion Plating

Ti(C, N) multilayer films have been prepared by closed-field unbalanced magnetron sputtering technology and using graphite target as the C supplier. Microstructural observation results showed that the Ti(C, N) films exhibited multilayer structure with most of fine nano-columnar Ti(C, N) grains existing in the films. The current of graphite target had an effect remarkably on the multilayer structure of films: the periodical thickness gradually increased as the current went up, but the grain size of films gradually decreased and even amorphous phase appeared as the current further increased. The microstructure of Ti(C, N) films changed from columnar crystallite to nanocomposite in high current of graphite target where the fine Ti(C, N) grains were distributed uniformly in the amorphous Ti(C, N) matrix, and the volume fraction of the amorphous phase increased with increasing current. Measurement results showed that the Ti(C, N) multilayer films have high microhardness and low friction coefficient, and especially the film deposited in the current of 0.9 A exhibits superior properties with optimizing hardness and friction coefficient. Based on the relationship of the microstructure and the properties of films, the multilayer structure and fine grain size of Ti(C, N) films are responsible for their well mechanical and friction properties. And choosing the graphite target as the C supplier is more propitious to decrease the friction coefficients of films.

Deposition of nano-scaled CrTiAlN multilayer coatings with different negative bias voltage on Mg alloy by unbalanced magnetron sputtering

In a magnetron sputtering system, the negative substrate bias voltage has been used as a basic process parameter to modify the deposition structure and properties of coatings. In this paper we report the effect of bias voltage ranging from −40 V to −90 V on nano-scaled CrN/TiN/CrN/AlN (CrTiAlN) multilayer coatings synthesized on a Mg alloy by a closed-field unbalanced magnetron sputtering ion plating system in a gas mixture of Ar + N 2. The technological temperature and atomic concentration in the multilayer coatings were controlled by adjusting the current density of different metal magnetron targets and the plasma optical emission monitor. The composition, crystallographic structure, deposition model and friction coefficient of multilayer coatings were characterized by X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ball-on-disc testing. The experimental results show that the deposition model and friction coefficient of nano-scaled CrTiAlN multilayer coatings were significantly affected by the negative bias voltage ( V b). The nitride species in multilayer coatings mainly involve CrN, AlN and TiN, and XRD analysis shows that the crystallographic structure was face-centered cubic. Under different bias voltage conditions, the multilayer coating composition shows a fluctuation, and the Al and Cr concentrations respond in the opposite sense to the bias voltage, attaining their greatest values at V b = −70 V. The surface and cross-sectional morphology shows deposition model change from a columnar model into non-columnar model with the increase in negative bias voltage. The friction coefficient of the nano-scaled multilayer coatings at V b = −55 V stabilize after 10 000 cycles.

Nanolayer CrN x/WN y coatings used on micro drills for machining of printed circuit boards

A series of CrN x/WN y nanolayer coatings were synthesized using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™), employing one W target and three Cr targets. For comparison, a monolayer CrN coating was also grown on the same deposition system. Characterization was conducted using EDX, SEM, TEM, AFM, XRD, nanohardness indentation tester, and scratch tester. Performance of cutting tools with the nanolayer coatings was carried out via machining tests using the coated micro drills to continuously make through-thickness holes on printed circuit boards. The results showed that nanolayer CrN x/WN y coatings with various modulation period ( λ) could be obtained on an industrial-size deposition machine by means of control in the current applied to the W target. Of the studied nanolayer CrN x/WN y coatings, the one with λ = 27 nm showed the highest nanohardness and best micro drilling performance. This nanolayer coating showed significant improvements in cutting performance as compared with the referred monolayer CrN coating.

A wear-resistant coating—Oxidized graded multilayer TiN/W coating

Combining sputtering technology using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™) with post heat treatment, a graded multilayer TiN/W coating, consisting of five layers, was synthesized and its outmost W layer was transformed to lubricious WO 3 successfully. The coatings were characterized by using GDOES, GXRD, a Rockwell C indentation tester, a nanoindentation tester, and a scratching tester. Wear behavior of coatings was evaluated by using a pin-on-disc tribometer. Through proper post heat treatment, the multilayer TiN/W coating, in spite of having a lower nano-hardness, showed good adhesion, much better wear performance and lower friction coefficient compared with the reference monolayer TiN coating.

Microstructure and tribological properties of TiN, TiC and Ti(C, N) thin films prepared by closed-field unbalanced magnetron sputtering ion plating

TiN, TiC and Ti(C, N) films have been respectively prepared using closed-field unbalanced magnetron sputtering ion plating technology, with graphite target serving as the C supplier in an Ar–N 2 mixture gas. Bonding states and microstructure of the films are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) in combination with transmission electron microscopy (TEM). The friction coefficients are measured by pin-on-disc test and the wear traces of deposited films are observed by optical microscope. Results show that the TiN film and Ti(C, N) film exhibit dense columnar structure while the TiC film exhibits a mixed microstructure of main nanocrystallite and little amorphous phases. The Ti(C, N) film has the highest microhardness value and the TiC film has the lowest. Because of small amount of pure carbon with sp 2 bonds existing in the film, the friction coefficients of Ti(C, N) and TiC multilayer films are lower than that of TiN film. In addition, the multilayer structure of films also contributes visually to decrease of friction coefficients. The TiC film has extremely low friction coefficient while the wear ratio is the highest in all of the films. The results also show that the Ti(C, N) film has excellent anti-abrasion property.

Structural and tribological properties of CrTiAlN coatings on Mg alloy by closed-field unbalanced magnetron sputtering ion plating

In this paper, a series of multi-layer hard coating system of CrTiAlN has been prepared by closed-field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique in a gas mixture of Ar + N 2. The coatings were deposited onto AZ31 Mg alloy substrates. During deposition step, technological temperature and metallic atom concentration of coatings were controlled by adjusting the currents of different metal magnetron targets. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). The structural, mechanical and tribological properties of coatings were characterized by means of X-ray photoelectron spectrometry, high-resolution transmission electron microscope, field emission scanning electron microscope (FESEM), micro-hardness tester, and scratch and ball-on-disc tester. The experimental results show that the N atomic concentration increases and the oxide on the top of coatings decreases; furthermore the modulation period and the friction coefficient decrease with the N 2 level increasing. The outstanding mechanical property can be acquired at medium N 2 level, and the CrTiAlN coatings on AZ31 Mg alloy substrates outperform the uncoated M42 high speed steel (HSS) and the uncoated 316 stainless steel (SS).

Structural, mechanical, and tribological studies of Cr–Ti–Al–N coating with different chemical compositions

In this paper, a multicomponent hard coating system of Cr–Ti–Al–N has been studied for its structural, mechanical and tribological properties under different chemical compositions. The coatings were deposited onto AISI M42 steel plates by closed-field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique in a gas mixture of Ar + N 2. Three processing steps in deposition involved were plasma ion cleaning, buffer layer deposition, and multicomponent layer deposition. During the final deposition step, nitrogen concentration was controlled at ∼ 50 at.% by using the feedback control of metal plasma optical emission monitor (OEM). The metallic ratio of Cr, Ti, and Al was varied by adjusting the currents of different magnetron targets. The coatings were characterized by means of energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectrometry (XPS), X-ray diffractometry (XRD), Rockwell-C indentation tester, microhardness tester, and pin-on-disc (POD) tribometer, in order to check their chemical composition, as well as to determine the structural, mechanical and tribological properties. The experimental results showed that the optimised quaternary Cr–Ti–Al–N coating performs better than the binary CrN as well as the ternary Cr–Ti–N and Cr–Al–N coatings in terms of hardness and wear resistance. The introduction of both Ti and Al elements into the CrN-based coatings enhances both of their mechanical and tribological performance.