Al2O3 Ball Research Articles

Friction and wear performance of hydrogenated diamond-like coatings with non-metal element complex dopants against alumina in ambient air

Diamond-like carbon coatings (DLCs) doped with non-metallic elements were deposited onto the surfaces of 316 L steel and silicon wafer substrates using plasma-enhanced chemical vapor deposition (PECVD) by controlling the working gas. Their microstructures and chemical bonding structures were characterized using scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The mechanical properties were investigated using a residual stress tester and nano-indenter. Pin-on-ball sliding tests against Al2O3 balls were performed on the coated 316 L specimens in ambient air. A phenomenological model of the friction behavior of DLCs was proposed. It was found that during friction, the surface material removal rate was mainly determined by the stiffness of the sp3C skeleton network. A high sp3C fraction is beneficial for reducing the removal rate. The DLCs doped with a trace of nitrogen had approximately the same sp3C fraction and wear rate as a-C:H films. Contrarily, the addition of Si and O elements reduced the sp3C fraction greatly and promoted surface material removal during friction. The CN, Si–N, and Si–O bonds in DLCs can pin and protect the sp2C-rich clusters from removal by dispersion-strengthening. Si/O binary dopants are helpful for the formation of a steady tribo-layer adhered to the counter-body ball surface to achieve a low coefficient of friction (CoF); however, Si/O/N tertiary dopants are degradable. In this study, pure a-C:H and DLC with trace amounts of nitrogen exhibited a minimum wear rate (1.2 × 10−16 m3/N m), while DLC doped with 9.14 at% Si and 3.51 at% O exhibited the minimum CoF value of 0.05.

Microstructure, Mechanical and Tribological Properties of Arc Ion Plating NbN-Based Nanocomposite Films.

NbN, NbN-Ag and NbN/NbN-Ag multilayer nanocomposite films were successfully deposited by an arc ion plating system (AIP), and their microstructures, mechanical and tribological properties were systematically investigated. The results show that all the films had a polycrystalline structure, and the Ag in the Ag-doped films existed independently as a face-centered cubic phase. The content of Ag in NbN-Ag and NbN/NbN-Ag films was 20.11 and 9.07 at.%, respectively. NbN films fabricated by AIP technique had excellent mechanical properties, and their hardness and critical load were up to 44 GPa and 34.6 N, respectively. The introduction of Ag into NbN films obviously reduced the friction coefficient at room temperature, while the mechanical properties and wear resistance were degraded sharply in comparison with that of NbN films. However, the NbN/NbN-Ag films presented better hardness, H/E*, H3/E*2, adhesive strength and wear resistance than NbN-Ag films. Additionally, analysis of wear surfaces of the studied films and Al2O3 balls using 3D images, depth profiles, energy dispersive spectrometry (EDS) and Raman spectra indicated that the main wear mechanisms of NbN and NbN/NbN-Ag films were adhesive and oxidation wear with slight abrasive wear, while the severe abrasive and oxidation wear were the dominant wear mechanism for NbN-Ag films.

High Hardness and Wear Resistance in AlCrFeNiV High-Entropy Alloy Induced by Dual-Phase Body-Centered Cubic Coupling Effects.

High-entropy alloys (HEAs) with high hardness are promising materials for advanced industrial manufacturing. In this study, the AlCrFeNiV HEA was designed and successfully prepared using a plasma instantaneous process. The hardness test showed that AlCrFeNiV had a high hardness of 1076 ± 15 HV, which was much higher than those reported in the literature. The microstructure of AlCrFeNiV was composed of two different types of body-centered cubic (BCC) structures, BCC1 (Al, Cr, Fe, and Ni) and BCC2 (enriched V and Cr). A mixture of different BCC systems produced solution strengthening, which was responsible for the superior hardness. Moreover, the reciprocating sliding wear behavior of HEA against Al2O3 balls under dry and lubricated conditions at ambient temperature was investigated. The wear rates of AlCrFeNiV against Al2O3 under dry wear and lubrication were 17.2 × 10−5 mm3 N−1·m−1 and 12.4 × 10−5 mm3N−1·m−1, respectively, which were of the same order of magnitude as the wear rates of BCC HEAs. Regardless of the dry wear or wear with lubrication, the wear mechanism of the HEA was abrasive and delamination wear.

Improving wear and corrosion protection of AISI 304 stainless steel by Al2O3-TiO2 hybrid coating via sol-gel process

ABSTRACT Al2O3, TiO2, and Al2O3-TiO2 coatings were deposited on AISI 304 stainless steel plates by the sol–gel dipping technique, and the effects of the coating composition on microstructure, wear, and corrosion characteristics were examined. Tribological features were determined by ball-on-disc sliding tests against an Al2O3 ball under a 10 N load, while corrosion properties were evaluated by potentiodynamic polarisation tests performed in 3.5% wt. NaCl solution. γ-Al2O3, α-Al2O3, and rutile phases were detected in the hybrid coatings. The highest coating thickness was obtained in single Al2O3 film and decreased with an increasing amount of TiO2 nanoparticles. The single Al2O3 layer had both the highest wear resistance and the lowest corrosion resistance. Although TiO2 addition caused an increase in the wear rate, it improved the corrosion resistance of the coating by filling the voids in the Al2O3 film. The Al2O3-TiO2 hybrid film with a relative ratio of 6:1 as a candidate for the wear- and corrosion-resistant coating decreased wear and corrosion losses of the 304 substrates by 83% and 97%, respectively.

Study on Friction and Wear Properties of 23CrNi3Mo Carburized Steel under Water Lubrication

In this paper the friction and wear of 23CrNi3Mo carburized steel under water lubrication were studied. The friction and wear properties of carburized steel sliding with stainless steel, GCr15, Al2O3 and ZrO2 balls were analyzed by tribometer, 3-D topography and SEM. The results show that compared with other materials, ZrO2 and carburizing steel have better tribological properties. Compared with Al2O3, the wear depth of carburized steel sliding with ZrO2 is reduced by 41% at the load of 2 N and 50% at the load of 10 N. In the load range of 2N-10N, the wear rate of carburized steel is the lowest when rubbing with ZrO2, and it gradually decreases when the load increases. Combined with SEM and Raman spectrum analysis, Oxide film was formed on the surface of carburized steel during the sliding test of ZrO2 and carburized steel. This oxide film was mainly composed of Fe3O4 and Fe2O3, which effectively reduces the friction coefficient and wear rate of 23CrNi3Mo carburized steel under water lubrication.

Microstructure and tribological properties of multilayered ZrCrW(C)N coatings fabricated by cathodic vacuum-arc deposition

In this study, a series of ZrCrW(C)N multilayer coatings with various transition layers were deposited on AISI304 stainless steel using cathodic vacuum-arc deposition in N2–C2H2 gas mixture. The tribological behaviors of sliding against Al2O3 balls under dry friction and lubricant conditions were investigated using a reciprocating tribometer. The results demonstrated that the ZrCrW(C)N coatings comprised (Zr, Cr, W) (C, N) crystallites and an amorphous carbon phase. It possessed a nano-hardness of 35.4 GPa and an elastic modulus of 417.7 GPa. The friction coefficient of the coating was reduced by 14% compared to that of the 304 matrices, and the wear mechanism changed from adhesive wear to slight abrasive wear under the lubrication steady state. Under dry friction conditions, the ZrCrW(C)N coatings with the entire CrWN transition layer exhibited wear rates of 1.27 ± 0.04 × 10−8 mm3 (N m)−1, which were one order of magnitude lower than that of the 304 steel. Compared with the untreated AISI304 stainless steel, the ZrCrW(C)N coating exhibits excellent mechanical and tribological properties under lubricated and dry friction conditions, which are crucial for engineering applications.

Microstructure, Mechanical, and Wear Properties of Al-Alloyed Austempered Ductile Irons

ABSTRACT Spheroidal graphite cast irons with 0-4 wt.% aluminum addition fabricated by green sand casting were austenitized at 900 °C for 90 min and subsequently austempered at 300 °C for 60 min. The samples were subjected to dry sliding wear tests against Al2O3 balls under various conditions. Microstructural analysis showed that increasing Al decreased the acicular ferrite ratio and disrupted graphite nodularity. Accordingly, UTS and hardness decreased while impact strength increased except for the 4 wt.% Al-alloyed cast iron. Al2O3 layer formed around graphite nodules could not be removed during the austempering and caused an increase in the mechanical strength of this sample. Sliding tests revealed that the wear resistance of the samples increased with sliding speed and decreased with applied load. Worn surfaces predominantly suffered from abrasion, adhesion, and delamination. Although lower Al addition increased wear losses, 4 wt.% Al-alloyed cast iron showed the best wear resistance.

Fe-based amorphous coating for high-temperature wear, marine and low pH environments

Fe-based amorphous coatings have been manufactured by the high-velocity oxygen fuel (HVOF) process to explore their applications for high-temperature wear, marine and acidic corrosion environments. The microstructural and mechanical characterization of the coating was performed using XRD, SEM-EDS, micro and nanoindentation techniques. The dry sliding wear performance of the coating was analyzed against an Al2O3 ball at room temperature (RT) and 600°C. In addition, the corrosion behaviour of coating was evaluated in filtered seawater and 0.5M H2SO4 solutions. The coating retained the amorphous state. Substantial enhancement in nano and micro-mechanical properties were observed after exposure at 600°C. Dry sliding wear tests indicated that the coating displayed three times better wear resistance at 600°C than at RT. The combined effects of enhanced mechanical properties due to nanocrystal precipitation and stimulated splat-to-splat cohesion behaviour and a compact, dense oxide glazed layer improved the overall wear resistance at 600°C. The coating exhibited higher corrosion resistance than 316L stainless steel and other Fe-based amorphous coatings in seawater and acidic solutions. In both environments, the coating demonstrated passivation behaviour derived from a layer composed of a stable Cr-based oxide reinforced with Mo and W-based oxides.

M-site solid solution of vanadium enables the promising mechanical and high-temperature tribological properties of Cr2AlC coating

Cr2AlC MAX phase coating exhibited excellent oxidation resistance and hot corrosion, but it typically suffered from low hardness and toughness as well as lack of lubrication at high temperature. With a solid solution design on M-site, we demonstrated that the hardness of the Cr2AlC MAX phase coating was enhanced by 34.3% when Cr was partially substituted with V (47 at.%), and the coating toughness was improved simultaneously. Furthermore, according to the high-temperature tribometer test, both the friction coefficient and the wear rate of the coatings at 900 °C against Al2O3 balls were significantly reduced at 47 at.% V. This could be attributed to the formation of a large number of molten V2O5 wrapped (Cr, Al)2O3 hard crystal grains, which not only provided a wide range of liquid-phase lubrication, but also prevented the coating from being apt to wear out. Different from the multi-phase compositing, this study suggested a promising strategy to enhance the combined mechanical and tribological performance of MAX phase coatings by M-site V solid solution for harsh applications at a high temperature of 900 °C.

Tribological properties of TiSiVN coatings: The effect of the counterpart on the wear performance

Self-lubricant coatings are a subject of continual research and improvements. In this research, the tribological performance of TiSiVN coatings produced by increasing V concentration is evaluated. The coatings were deposited by high-power impulse magnetron sputtering in deep oscillation mode, and were tested against three different counterparts (Al2O3, stainless steel and Titanium). The wear mechanisms were identified and the tribolayer was characterized to correlate with different specific wear rates and friction coefficient values. The coatings tested against Al2O3 balls displays a polishing type wear mechanism with some material adhered to the film wear track surface. When V is added to the reference film, V-O formed on the wear track has a beneficial influence by decreasing the friction and the wear of the coatings. For stainless steel balls, the wear track displays a mixture of severe abrasion and adhesion wear. Enclosure of hard particles at the softer stainless steel ball is the cause for the severe abrasion of the coating surface. This harsh abrasion removes the V-O from the contact and consequently decreases the efficiency of reducing friction coefficient and wear when compared to the tests against Al2O3 balls. For tests conducted against Ti ball, a strong adhesion of the material to the counterpart is observed. The adhered material protects the coatings from wear by giving rise to similar friction coefficient values irrespective of the coatings’ chemical composition.

Tribological behaviour of a multilayer CrN/DLC coating obtained using PVD-MS

Diamond-like Carbon (DLC) coatings are used as protective layers for steel components due to their hardness, chemical inertia and interesting tribological properties. Reducing wear and friction coefficient is of great importance for industries today in order to increase energy efficiency and reduce harmful emissions to the environment. In this paper, a multilayer CrN/DLC coating is analysed. It was deposited using a commercial Plasma Enhanced Magnetron Sputtering over nitrided and not nitrided mild-alloy steel AISI 4140, produced for the first time in Argentina, at the firm Coating.Tech by Flubetech-Tantal. The base of the coating is an anchor layer made of CrN and the top layer is a chromium-dopped hydrogenated amorphous carbon (a-C:H:Cr), which provides excellent tribological properties. Wear tests were carried out in a Pin-on-Disk apparatus, using an Al2O3 ball as counterpart, with Hertzian contact stress from 1370 up to 1460 MPa. The friction coefficient was μ ∼ 0.1, which is 80% less than the untreated steel and the wear volume loss was reduced several times. The adhesion was evaluated by means of Scratch Test, where major improvement was noticed in the samples which were nitrided as pre-treatment, increasing critical load from 25 N up to 65 N.

Electrostatic and tribological properties of hydrogenated diamond-like carbon on anodic aluminium oxide

The electrostatic and tribological properties of three types of anodic aluminium oxide (alumite) and hydrogenated Diamond-Like Carbon (DLC) on alumites were investigated. It was first proven that an ultrathin DLC at 5 nm on an insulative surface exhibits slow discharge. For alumites, clear electrostatic discharge behaviour was not observed in spite of the fact that surface resistance was in the dissipative region of 1010 Ω. Upon coating alumites with a hydrogenated DLC, slow charge and discharge were observed. DLC coatings on alumites significantly improved dielectric strength and hardness due to DLC's intrusion into the porous structure of the alumites. The coefficient of friction on alumites, which stood at 0.9 against Al2O3 and E52100 balls, was much improved to 0.1 with a DLC coating, and so was wear loss and life time.

Investigation of Dry Sliding Friction, Wear and Mechanical Behavior of the Ti-6Al-7Nb Alloy after Thermal Oxidation.

The mechanical and tribological characteristics of the Ti-6Al-7Nb alloy were investigated within a wide range of temperature and time parameters of thermal oxidation. The hardness, HIT, and indentation modulus, EIT, of the alloy in question, with and without an anti-wear oxide layer, were determined. The tribological properties of sliding couples were studied under technically dry friction conditions, using a ball-on-disc tribometer. The test pieces were non-oxidized and oxidized Ti-6Al-7Nb alloy discs, and Al2O3, ZrO2, and 100Cr6 balls were used as counter specimens. After thermal oxidation, the surface of the titanium alloy was characterized by a significantly higher hardness, HIT (8–10 GPa), compared to the surface not covered with oxide layers (3.6 GPa). The study showed that the curvature of the loading segments increased with an increasing oxidation temperature, indicating a strong positive dependence of hardness on the thermal oxidation temperature. The value of the indentation modulus, EIT, was also found to increase with the increasing oxidation temperature. The intensity of the tribological processes was strictly dependent on the oxidation parameters and the couple’s material (Al2O3, ZrO2, 100Cr6). It has been shown that the thermal oxidation process makes it possible to control, within a wide range, the friction-wear characteristics of the Ti-6Al-7Nb alloy.

PEEK/graphite film formation on microgrooves of PEEK- hybrid radial Al2O3 ball bearings under rolling contact in dry condition

The influence of PEEK (Polyether ether ketone) composite solid lubricant film on hybrid radial polymer bearing life, consisting of PEEK ring-PTFE (polytetrafluoroethylene) /graphite retainer-alumina balls, was investigated in terms of self-lubrication properties. A PEEK/graphite film layer formed around the ‘pure rolling contact’ track in the Hertzian contact area of the PEEK ring during rolling contact under dry conditions, and then covered the whole contact track. The PEEK/graphite film growth maintained smooth rotation of the bearings, avoiding seizure. Microgrooves on the PEEK ring strongly influenced the formation of PEEK/graphite film. This result helps effective tribological design of micro grooves for polymer bearings.

Structural, mechanical, and tribological studies of Ni-B-TiN composite coating: effect of SDS concentration

In industrial applications, it has been desired to be durable and used for a long time in harsh working conditions. As an alternative study, the effects of surfactants on TiN particle distribution, particle content in the coating, microstructure, surface morphology, hardness, and wear resistance were investigated. Scanning electron microscopy (SEM) was used to characterize the surface and cross-section images of Ni-B-TiN composite coatings. The SDS concentration in the electrolyte affects the TiN particle distribution, resulting in a uniformly distributed surface morphology of the composite coating. The crystal properties of the elements in the composite coating were examined using X-ray diffraction (XRD). The surfactant directed the Ni crystal in the (111) plane, affecting the preferred direction of the grains. The distribution of TiN particles in the Ni-B alloy matrix with Zeta potential was investigated. The mechanical properties of composite coatings were evaluated over average values by performing tests from different zones under a max. 50 mN load using the Nanoindentation technique. The tribological behavior of Ni-B-TiN composite coatings sliding towards Al2O3 balls (Ø 6 mm) was investigated with a CSM tribometer device void of lubrication at room temperature. In this study, the usability of SDS (sodium dodecyl sulfate)-anionic surfactant for Ni-B-TiN metal matrix composites deposited on mild steel substrates by the electrodeposition method has been explained.

Volume fraction effect of stainless steel on microstructure, interface, corrosion and wear behavior of stainless steel / aluminum bimetal composites

304 stainless steel (SS)/A356 aluminum bimetal composites were manufactured by vacuum-assisted melt infiltration casting successfully. SS chips with different volume fractions of 35%, 50%, 60%, and 65% were used in a composite structure. Low-cost, environmentally friendly production was achieved by using chips as reinforcing material. Dry sliding ball-on-disc tests were performed against Al2O3 ball under a load of 10 N. Potentiodynamic polarization analysis was carried out in 3.5% NaCl solution. θ (Fe4Al13) and η (Fe2Al5) phases developed at the SS/Al interfaces. Abrasive and adhesive wear predominated worn surfaces, whereas galvanic and pitting corrosion mechanisms originated during potentiodynamic polarization tests. Lower volume fractions of SS chips resulted in microploughing, while their higher amounts caused microcutting during sliding. Moreover, the samples containing 60% and 65% SS failed in the corrosion tests due to the lack of passivation. The most suitable SS ratio was determined to be 50%, considering microstructural, interfacial, tribological, and anti-corrosion features of SS/Al bimetal composites.

The synergistic mechanism between transfer layer and surface passivation of diamond-like carbon film under different gas pressure environments

The low friction behavior and mechanism of diamond-like carbon (DLC) film are studied under different gas pressure environments. The results present that DLC film against Al2O3 and steel balls shows a relatively stable friction coefficient in the air environment, but it shows an unstable and relatively low friction coefficient under gas pressure of 5 Pa. Under gas pressure of 10−3 Pa, the DLC film fails rapidly although it achieves a short superlubricity state. With the decrease of gas pressure, the gas passivation effect on the surface of DLC film will be weaker and weaker while the formation degree of transfer layer will be more and more continuous and dense. The first-principles calculations imply that interfacial adhesion has a significant influence on the formation of tribofilms and surface wear. Further analysis shows that the low friction behavior and mechanism of DLC films in air, low vacuum (5 Pa) and high vacuum (10−3 Pa) environment are not controlled by graphitization mechanism, but are caused by the synergistic action of transfer layer mechanism and surface passivation mechanism.

Experimental study on the treatment of oil-based drill cutting by pulsed dielectric barrier discharge plasma at atmospheric pressure

Oil-based drilling cuttings produced in the process of oil exploration and shale gas development are harmful to the ecological environment. The emerging low-temperature plasma technology has shown potential for environmental protection. In this paper, pulsed dielectric barrier discharge (DBD) plasma was used to treat contaminated drilling cuttings at atmospheric pressure. The effect of adding active aluminium oxide (Al2O3) balls to the oil-based cuttings on the degradation rate of mineral oil was evaluated. Results showed that when the oil-based drilling cuttings were mixed with active Al2O3 balls, the highest degradation rate of mineral oil (68.1%) was achieved when the treatment time was 30 min. This rate was 41.8% higher than that obtained by DBD treatment alone. The Fourier transform infrared spectroscopy showed that the content of alkanes in the treated samples decreased significantly. The gas chromatography-mass spectrometry and ion chromatography analysis showed that formic acid, acetic acid, and other by-products were formed. The contents of C and H in the samples treated by DBD decreased. Overall, this study provides much-needed insights into the reaction mechanism and pollutant degradation process of the synergistic treatment system of pulsed DBD and active Al2O3 balls in the field of oil-based drilling cuttings treatment.

In-situ TiB2 and Fe2Ti intermetallic assisted hard coatings by Fe-Ti-B based hardfacing electrodes

The aim of this study was to form Fe2Ti and TiB2 phases on the steel surface in-situ using ferroalloy starting materials and to investigate the changes in the surface properties such as microstructural, hardness, wear and corrosion behavior. To this end, Fe(18−X)TiXB2 (x = 3–5) based hardfacing electrodes were produced and coated on AISI 1010 steel substrate using electric arc welding method. The development of the substrate-coating interface, solidification behavior and microstructural conditions of the samples were examined using a variety of characterization methods. In the coating microstructures, intermetallic phases such as TiB2 and Fe2Ti, α-Fe + Fe2Ti eutectic structure and trace amounts of non-equilibrium phases were detected. It has been understood that these phases formed in the microstructure have important effects on the hardness, wear and corrosion resistance of the coating. In the hardness test performed by nanoindentation method, very high hardnesses such as 3254 (± 26) HV in TiB2 phase and 1130.1 (± 13) HV in Fe2Ti phase were measured. As a result of the ball on disc reciprocal wear test performed against Al2O3 ball at different loads, it has been observed that titanium has an effect on the friction coefficient, and the wear resistance increases with the increasing amount of titanium in the electrode cover composition. In addition, according to the potentiodynamic polarization test results carried out in 3.5% NaCl solution, it has been determined that the corrosion potential increased with increasing titanium in the electrode cover composition, there was no linear change detected in the current density.

Influence of Combined Mechanical Processes on Tribological Properties of Tool Steels Vanadis 8 and Vancron 40 With a Similar Hardness

Surface integrity is important factor for components exposed to wear, like cold working tools, which need to possess high hardness combined with high wear resistance. Surface treatments such as grinding, hard turning, and hard turning with slide burnishing have been developed for its improvement. Vancron 40 and Vanadis 8 tool steels, of different chemical composition and different types and amounts of carbides, were now investigated. Heat treatment was carried out in vacuum furnaces with gas quenching to hardness of Vancron 64 ± 1 HRC and of Vanadis 65 ± 1 HRC. 3D topography, optical and scanning electron microscopy, X-ray diffraction and ball-on-disc tribological tests against Al2O3 and 100Cr6 balls as counterparts were used to examine wear and friction. For both steels, the lowest values of dynamic frictions and wear rates against Al2O3 counterbodies were achieved after sequential process of hard turning with slide burnishing with a burnishing force of 180 N. For alumina balls, the increase of wear resistance, achieved after hard turning plus burnishing in comparison to grinding exceeds 50 and 60%, respectively for Vanadis 8 and Vancron 40 steels.