Ball-on Disc Research Articles

Wear properties of a new Al80Mg10Si5Cu5 multicomponent alloy

The present study investigates the tribological properties of a newly developed multicomponent aluminium weight-light multicomponent alloy for wear based on the Al80Mg10Si5Cu5 system for lightweight automotive applications, especially back drum discs. The samples were manufactured by High-Pressure Die Casting (HPDC) employing cast alloy returns and secondary aluminium ingots and were tested at room temperature (RT) and 200 °C. It has been observed that the Al80Mg10Si5Cu5 alloy offers a higher hardness and wear resistance at RT and especially at 200 °C compared with the AlSi9Cu3 reference alloy (x10 times reduction in wear rate). The impact of maintaining the external surface layer (skin) of HPDC cast parts has been studied for the ball-on disc test, showing improved tribological properties and the possibility of avoiding the machining of contact surfaces. The as-cast Al80Mg10Si5Cu alloy with the surface layer showed a wear rate coefficient of 5 × 10−4 mm3/N.m2 at RT, a 50 % lower than that of the sample without skin. Solution heat-treated samples (72 h at 440 °C, water quenching at 75 °C, and natural aging) with the surface layer showed a wear rate coefficient of 11 × 10−4 mm3/N.m2, approximately 20 % lower than the sample without a surface layer. The wear rate of AlSi9Cu3 alloy decreased by more than 50 % in the samples without skin at RT. At 200 °C, wear rate coefficients were lower in the samples with the surface layer.

Elevated temperature wear and friction performance of WC-CoCr/Mo and WC-Co/NiCr/Mo coated Ti-6Al-4V alloy

The effect of adding Mo to WC-based coatings on the microstructure and dry sliding wear performance at elevated temperatures is investigated. The WC-based coatings are deposited using a high-velocity oxy-fuel process on the titanium-31 substrate. The coating was characterized by microstructure, microhardness, porosity, surface roughness, density, and bond strength. The wear and friction behavior of coatings was evaluated using a ball-on disc tribometer at temperatures of 200, 400, 600, and 800 °C and loads of 20 and 30 N. SEM-EDS and an optical profilometer were utilized to evaluate the wear rate and mechanism. The microhardness and bond strength of WC-CoCr/10%Mo coating is more than that of WC-Co/20%NiCr/10%Mo coatings. The WC-CoCr, WC-CoCr/10%Mo, and WC-Co/20%NiCr/10%Mo coatings exhibited decreasing wear rates up to 600 °C, transitioning to an increase at 800 °C. The oxide phases of CoWO4, WO3, MoO3, CoMoO4, and NiMoO4, formed at 600 °C, aid in reducing the rate of wear and friction coefficient. However, the wear rate slightly increased at 800 °C due to vigorous oxidation and softness of coatings. The friction coefficient of WC-CoCr, WC-CoCr/10%Mo, and WC-Co/20%NiCr/10%Mo coating decreases with increasing temperatures due to the lubricating properties of oxide phases on the worn surface. The WC-CoCr/10%Mo coating demonstrates a lower friction and wear rate than the WC-CoCr and WC-Co/20%NiCr/10%Mo coating. At 200 °C, the predominant wear mechanisms were abrasive and fatigue wear, while at 800 °C, oxidative wear, abrasive wear, and adhesive wear were observed.

Tool Surface Degradation and Adhesion in Aluminium Forging

Tool surface deterioration is a crucial effect limiting the efficiency of forging processes. Prior work on wear is limited to steel forging while investigations on tribology in aluminium forging are limited to an abstract or simplified level. The presented work aims at contributing to filling this gap with a holistic analytic approach including ball-on-disc (BoD) tests, ring compression (RC) tests and serial forging (SF) tests close to industrial applications in order to gain insights on effects and influences of surface deterioration and evaluate the suitability of different tool coatings. The results show that the primary influence on surface adhesion in aluminium forging is the superposition of surface enlargement and contact pressure of the material flow. Duplex-treated tools with the combination of a nitriding in the first step and an additional coating with chromium nitride (CrN) afterwards show a significant reduction of aluminium adhesion in ring compression and serial forging tests, representing a promising approach to tool life enhancement in forging applications.

Fine Blanking of Austenitic Stainless Steel Gears Using Carbon-Supersaturated High-Speed Steel Tools

Austenitic stainless steel gears were fabricated via the fine blanking process that can be used for mass production. A carbon-supersaturated (CS)-matrix high-speed steel punch was prepared to minimize the adhesive and abrasive wear damage. Its edge profile was tailored and finished to control the local metal flow around the punch edges and edge corners. This CS punch was utilized in fine blanking the AISI304 austenitic stainless steel gears. Ball-on-disc (BOD) testing was first employed to describe the frictional behavior of the CS tool steel disc against the AISI304 stainless steel balls. SEM-EDX analysis on the wear track revealed that a free-carbon tribofilm was formed in situ in the wear track to prevent adhesive wear via galling on the tool steel disc. No significant adhesive or abrasive wear was detected on the punch edges and punch edge corners after continuously fine blanking with 50 strokes. AISI304 gears were produced to have fully burnished surfaces. Their pitches, widths and circles were measured to evaluate their gear-grade balancing during the fine blanking process. The stabilized gear-grade balancing in JIS-9 to JIS-10 grades was attained for these as-blanked AISI304 gears without finishing processes.

The effect of processing parameters on the wear properties Al6061/GNP composites produced by hot pressing

In the present study, the effect of graphene nanoplatelet (GNP) reinforcement in Aluminum material at different rates was investigated on tribological properties. In this scope, the samples were produced by the hot press under determining different production parameters. The wear characteristics of the composites were determined using the ball-on disc wear test method. Ball on disc wear test showed that the Al6061/GNPs composite which was produced with the addition of 1 wt% GNPs, a sintering temperature of 600 °C, and a sintering time of 45 min, had the best wear resistance. Thanks to the GNPs reinforcement, a 61 % reduction in wear rate was achieved when compared to the non-reinforced Al material. The effects of the production parameters on the friction coefficient were investigated using the Taguchi method and it was determined that the most important parameter affecting the friction coefficients of the composites was the wt % GNPs addition. The results showed that the addition of GNPs is an important reinforcing material that reduces the wear rate when added to the structure at certain rates.

WE43 Magnezyum Alaşımının Soğuk Sprey Kaplama Yöntemi ile Al/Zn/Al2O3 ve Zn/Al2O3 Kaplanması ve Aşınma Davranışlarının İncelenmesi

Mg alaşımları otomotiv, uçak, uzay ve haberleşme sektörlerinde düşük özgül ağırlıkları ve yüksek mukavemetli olması nedenleriyle tercih edilmektedir. WE serisi, Mg, Y, Nd, nadir toprak elementlerini içeren Mg alaşımları serisidir. Bu alaşım serisi için sürünme dayanımı iyi olsa da aşınma dayanımı gelişmeye açıktır. Bu çalışmada amaç, özgül ağırlıkları nedeni ile kullanım potansiyeli yüksek olan WE43 Mg alaşımlarının aşınma dayanımını arttırabilecek kaplamaların, endüstride de kolaylıkla uygulanabilecek bir yöntem kullanarak geliştirilmesidir. Bu amaçla soğuk sprey kaplama yöntemi kullanılarak aynı zamanda yüzeyleri fazlasıyla aktif olan magnezyum alaşımlarının oksitlenmeden kaplanması sağlanmış ve aşınma dayanımı geliştirilmiştir. Yüzeyleri ince kumlama işlemiyle pürüzlendiren WE43 Mg alaşımları soğuk sprey yöntemi kullanılarak Al/Zn/Al2O3 ve Zn/Al2O3 içerikli ve ticari isimleri sırasıyla DYMET K-20-11 ve DYMET K-00-11 olan tozlar kullanılarak 500ºC sıcaklıkta N2 koruyucu gaz atmosferi altında süpersonik hızlardaki tozlar için 6 g/dak. toz besleme hızıyla altlıklar üzerine püskürtülmüştür. Farklı içerikli tozlarla kaplanmış ve kaplanmamış numunelerin morfolojik analizleri SEM ve XRD yöntemleri ile incelenmiş, kaplama kalınlıkları kesitten alınan SEM görüntülerinden ölçülmüş, EDS analizleri ile elementlerin yüzde oranları tespit edilmiştir. Ayrıca aşınma performansının incelenmesi için ball-on disk aşınma testlerinden hacim kayıpları değerlendirilmiştir. Sonuç olarak, soğuk sprey kaplamalarla, kaplamasız duruma göre WE43 alaşımlarının aşınma kaybı yaklaşık %40 oranında azalmıştır.

The effect of FSP on the friction and wear behaviour of Al5083 under normal atmosphere and vacuum conditions

In current technology, there are a lot of machines that work under vacuum conditions such as in space and aviation. For this reason, friction and wear properties of especially light metals, such as aluminium and magnesium alloys, which are candidates to be used in such areas should be examined under vacuum conditions. In this study, the effect of friction stir processing parameters such as traverse speed and pass number on the microstructure, hardness and wear properties of the Al 5083 alloy were investigated. During the friction stir processing, three traverse speeds and from 1 to 4 passes were applied to the surface of the samples. The wear behaviour of the processed and unprocessed samples was investigated by using the ball-on disc tribometer under air and 5 × 10−3 mbar vacuum conditions. After friction and wear experiments, all FSPed samples showed lesser wear amount under vacuum conditions compared with air conditions.

The Affect of Aging Process on Wear Properties of Al6061/GNP Metal Matrix Composite

In this study, affect of aging on wear characteristics of the nano GNP reinforced Al6061 metal matrix composites. In this scope, the samples were produced by hot press at 500 ℃ temperature under 50 MPa pressure for 30 minutes. The wear characteristics of the composites were determined using the ball-on disc wear test method. The affect of aging on the friction coefficient and wear ratio were investigated. Graphene reinforcement significantly increased the friction coefficient between the stainless steel ball and specimen but aging process lowered the coefficient of friction to a better level. Also artificially aged specimens showed significant increase in hardness values. Key factors are affecting the mechanical performance of the Al based alloy is reinforcement and aging process.

PROPERTIES of Al2O3 CERAMIC COATINGS APPLIED BY ALD METHOD ON 100Cr6 STEEL

The purpose of the paper was to assess the morphology, chemical composition, geometric surface structure and contact angle, as well as to analyse the tribological properties of Al2O3 coatings deposited on 100Cr6 steel using the technique of atomic layers ALD. Al2O3 coatings were selected due to their tribological properties, adhesion to the substrate and hardness. Tribological tests were performed in a reciprocating motion in a ballon- disc combination, with a counter-specimen of 100Cr6 steel, under the conditions of technically dry friction. Surface morphology was observed under a scanning microscope, and an EDS analyser enabled the performance of an analysis of the chemical composition of the samples. Wetting of the surface of the Al2O3 coating was determined by means of an optical strain gauge. The geometric surface structure before and after the tribological tests was analysed by means of a confocal microscope with an interferometric mode. The tests proved that during technically dry friction, the average coefficient of friction for the Al2O3 coating is lower by approximately 30% than for 100Cr6 steel. The tested coatings are characterised by hydrophobicity.

EFFECT OF LOADS AND BIO-LUBRICANTS ON TRIBOLOGICAL STUDY OF ZIRCONIA AND ZIRCONIA TOUGHENED ALUMINA AGAINST Ti6Al4V FOR HIP PROSTHESIS

Zirconia and zirconia toughened alumina (ZTA) are widely used for biomedical applications. Owing to the superior mechanical and bio-compatible properties of ZTA, it is now gaining more importance over zirconia, as it has the profound strength of zirconia and alumina. This study examines the tribological behavior of Zirconia and ZTA balls sliding against a Ti6Al4V disc using the Ball-on-disc (BOD) Tribometer. The effect of loads and bio-lubricants influencing the tribological behavior is investigated for a sliding distance of 2[Formula: see text]km using BoD Tribometer. The friction and wear coefficients are examined under these loading and lubrication conditions. Five bio-lubricants considered for the tribological study of biomaterials include ringer’s solution, phosphate buffer saline (PBS), distilled water, NaCl 0.9% saline solution and sesame oil. The result showed that ZTA had a lower coefficient of friction (CoF) value of 0.34 for NaCl bio-lubricant. The ZTA and zirconia exhibited the least wear coefficient values under sesame oil lubrication. Overall, ZTA had better CoF under high loads for PBS, distilled water and sesame oil bio-lubricants. However, zirconia exhibited a better wear coefficient under all loads and lubrication conditions.

Wear of a rough disc in dry sliding contact with a smooth ball: experiment and modeling

The main objective of this work is to model wear of a disc which was subjected to dry contact with a ball in unidirectional sliding. Tribological tests of sliding pairs were carried out using a tribological tester T-11 in a ball-on disc configuration. Stationary balls made of 100Cr6 steel with a hardness of 62 ± 2 HRC co-acted with rotating discs with 42CrMo4 steel with a hardness of 40 ± 2HRC. Discs were machined by lapping, grinding, milling, and vapour blasting. The values of the Sq parameter of disc surfaces were between 0.1 and 5.86 µm. Wear volumes of the discs were lower for bigger roughness heights. The simulation of disc wear was conducted on the basis of the repetitive contact between sliding surfaces. Strong correlation was achieved between the modeled and measured volumetric wear levels.

Investigation on Wear Behavior of Steels Coated with WC by ESD Technique

Electro-spark deposition (ESD) or low energy welding (LEW) technique allows the coating of metallic materials with different metal and alloys, conductive ceramics and conductive ceramic metal composites. It is also known as micro-joining process to improve the wear properties of the substrate or to obtain a more durable upper superficial coating. In this study, the surfaces of AISI 1040, AISI 4140 and AISI 5140 steels were coated with WC electrode at constant rotational speed and then characterized by a metallographic study. A homogeneous coating thickness was observed in microscopy studies and the formation of W2C phase in the coating layer was determined in XRD analysis. Hardness of WC coated samples increased approximately 5 times. Abrasion tests were carried out by ball-on disc method with WC–Co ball at 250 m under 5N load. In the abrasion tests with WC–Co ball, the best abrasion resistance is obtained with WC coated AISI 5140 steel, while the lowest strength is obtained with uncoated AISI 4140 steel.

Investigation of the high temperature dry sliding wear behavior of graphene nanoplatelets reinforced aluminum matrix composites

In this study, graphene nanoplatelets (GNPs) with a thickness of 50-100 nm have been utilized to improve the mechanical and tribological properties of A360 alloy due to their extraordinary mechanical properties and solid lubricant nature. For the investigation of tribological properties, ball-on disc tests were carried out at various temperatures including room temperature (RT), 150 °C, and 300 °C. According to the hardness and ball-on-disc test results, the nanocomposite samples reinforced with GNPs exhibited improved hardness and wear resistance. The improvement in the wear behavior of nanocomposites was referred to the temporarily formed solid lubricant film of harder GNPs during the wear, and hence coefficient of friction (COF) and volume loss were considerably reduced. Abrasive-adhesive, oxidative, and mild-to-severe were found to be main wear mechanisms at RT, 150 °C, and 300 °C, respectively. Overall, the results show that the nanocomposites fabricated by casting method combined with mechanical stirring and ultrasonication have promising wear performance, especially at elevated temperatures. This may suggest that these developed materials could be potential candidates to be used in the engineering applications requiring high temperature wear performance.

Microstructure, mechanical and tribological properties of VCN-Ag composite films by reactive magnetron sputtering

A series of VCN-Ag films with different Ag content were deposited by the magnetron sputtering system. The microstructure, mechanical and tribological properties of VCN-Ag films were characterized by X-ray diffractometer (XRD), Raman spectrometer, transmission electron microscopy (TEM), scanning electron microscopy (SEM), nano-indentation and ball-on disc tribo-meter. The results showed that the deposited VCN-Ag films consisted of face-centered cubic (fcc) Ag, fcc-VCN, tetragonal (t) V5CN and amorphous graphite and CNx phases, and nano-crystalline Ag was dispersed in the films. The addition of Ag below 0.72 at.% into the film increased the hardness, however, the hardness decreased rapidly when the Ag content was increased furtherly. The initial introduction of Ag into the film led to the lowering of the film's room-temperature wear rate, nonetheless, the wear resistance deteriorated when the Ag content was further increased. However, the friction coefficient of the films at room temperature increased monotonically as the content of the Ag increased. As for elevated temperature tribological properties of the film at 3.03 at.% Ag, there was an initial increase in frictional values but, when the temperature was above 300 °C the frictional values declined. More so, the wear rate increased monotonically when the temperature increased from 100 °C to 500 °C.

Experimental and Finite Element Wear Study of Silicon Nitride Against Alumina for Hip Implants with Bio-Lubricant for Various Gait Activities

This paper presents an experimental approach to predict the friction and wear coefficients followed by finite element modeling (FE) to analyze the wear of silicon nitride sliding against alumina bearing components up to 2 years considering risky gait activities. First, the friction and wear coefficients were determined for four loading conditions - 15, 20, 25 and 30 N for 20 km (equivalent to 2 years of implant life) using ball-on-disc (BOD) tribometer with 0.9% (NaCl) saline solution to simulate a lubricating bearing contact similar to hip joint. These BOD loads were equivalent to gait loads which were named as four groups- A (as similar to sitting down or getting up), B (as similar to stair ascending and descending with load), C (as similar to carrying load 50 kg) and D (as similar to load transfer 50 kg). Interestingly, the experimental results showed the friction and wear coefficients obtained from BOD tests were found to be much lower for higher gait loads due to the formation of discontinuous tribofilm on the worn surface. Later, finite element simulation was carried out and the findings revealed that physically demanding gait activity of load transfer 50 kg had the least maximum linear and volumetric wear. Group A gait activity showed maximum linear and volumetric wear among all the groups. From these results, it is quite evident that, people engaged in physically demanding gait activities, may prefer silicon nitride and alumina combination for hip joint replacement which showed reduced wear for risky activities.

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

The aim of the paper was to discuss different effects, such as, among others, agglomeration of selected nanoparticles, particularly those from zirconia, on the tribological behavior of lubricants. The explanation of the difference between the concepts of ‘aggregation’ and ‘agglomeration’ for ZrO2 nanoparticles is included. The factors that influence such an agglomeration are considered. Classification and thickeners of grease, the role of additives therein, and characteristics of the lithium grease with and without ZrO2 additive are discussed in the paper. The role of nanoparticles, including those from ZrO2 utilized as additives to lubricants, particularly to the lithium grease, is also discussed. The methods of preparation of ZrO2 nanoparticles are described in the paper. The agglomeration of ZrO2 nanoparticles and methods to prevent it and the lubrication mechanism of the lithium nanogrease and its tribological evaluation are also discussed. Sample preparation and a ball-on disc tester for investigating of spinning friction are described. The effect of ZrO2 nanoparticles agglomeration on the frictional properties of the lithium grease is shown. The addition of 1 wt.% ZrO2 nanoparticles to pure lithium grease can decrease the friction coefficient to 50%. On the other hand, the agglomeration of ZrO2 nanoparticles in the lithium grease can increase twice the friction coefficient relative to that for the pure grease.

Synergistic effect of talc/carbon spheres composite as oil‐based additive enhancing the lubricating properties for steel‐steel contact

AbstractTalc/carbon spheres (TC) composite was successfully fabricated through a simple and eco‐friendly hydrothermal method. The tribology properties of the base oil were significantly improved after adding TC composites, which had been studied by a ball on disc (BOD) tribometer. The friction coefficient of oil containing 0.5‐wt% TC composite (0.5 TC‐Oil) was only 0.08, with a decrease of 35.3% compared with the base oil at 5 N. Moreover, severe abrasive wear between friction pairs changed into slight plastic deformation lubricated with 0.5 TC‐Oil, as confirmed by scanning electron microscope (SEM). These results reflected notable synergy between self‐repair performance effect of talc and ball‐bearing effect of carbon spheres. The study displayed the potential lubricating performance of the TC composite in current generation oil lubricants.

Characterization and wear behavior of TiBC coatings formed by thermo-reactive diffusion technique on AISI D6 steel

A two-step Thermo reactive diffusion processes (including an initial titatinizing step followed by boronizing) is proposed in order to obtain superhard complex TiBC coating layer on AISI D6 steel. Microstructural characterization and mechanical properties of obtained TiBC layer conducted by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical microscopy, 2D profilometer, X-ray diffraction (XRD), micro-hardness, nano-indentation hardness and ball-on disc wear tests. Wear tests were carried out in ball on disc device by applying 30 N load and 500 m sliding distance against WC abrasive ball. Microstructural studies revealed a compact, homogenous and crack-free TiBC layer with 0.29–1.91 surface roughness (Ra), 3.65–29.5 μm thickness and 1800–4841 HV0.05, hardness and 146–235 GPa elastic modulus. Hardness values of TiBC layers was significantly higher than those obtained by standard titanizing and boronizing due to the interspersed TiB and TiC phases within the TiBC layer. Higher hardness values are highly effective on the wear resistance and wear type. Thus, in parallel with the increase in mechanical properties, wear resistance increased in the range of 4–120 times in comparison with the untreated AISI D6 sample. Severe wear and extensive plastic deformation was observed in the untreated AISI D6, while micro-cutting, micro-cracking and pitting was dominant in samples with hardness 1800–4000 HV. When the surface hardness reached values above 4000 HV the wear mechanism further changed to microcracking and spalling.

A tribological investigation of SLM fabricated TC4 titanium alloy with carburization pre-treatment

The tribological properties of SLM fabricated TC4 discs (before and after carburization) sliding against ZrO2 ball at different loads (0.98–4.94 N) under bovine serum lubricated conditions were investigated by using a Ball-On-Disc (BOD) tribo-meter. In comparison, the friction and wear behaviors of the forging fabricated TC4 disc against a ZrO2 ball were performed under the same lubricated condition, and the results represented the similar trends with the SLM fabricated TC4 (SLM -TC4). Meanwhile, the friction coefficients of SLM-TC4 and SLM-C-TC4 disc (SLM fabricated TC4 after carburization) against ZrO2 ball both decreased with the increase of the load. Combined with the worn surface analysis and theoretical analysis, it can be concluded that the friction force of the sliding pairs mainly originated from the resistance of deformation and shear stress, and the friction coefficients are linearly correlated to negative one-third power of the normal load. Furthermore, a hard TiC layer was observed on the surface of SLM-C-TC4 disc, which may provide a certain anti-wear capacity between the sliding pairs because of its effective resistance to deformation and shear stress. Therefore, the SLM-C-TC4/ZrO2 bearing couple showed significantly lower wear than that of the SLM-TC4/ZrO2 bearing couple and forged TC4/ZrO2 sliding pair. So, SLM-C-TC4 may be more suitable for joint prosthesis design.

A COMPARISON OF TRIBOLOGICAL PERFORMANCES OF Al2O3 AND Al2O3 + 40 wt .% TiO2 COATINGS MANUFACTURED BY ATMOSPHERIC PLASMA SPRAYING

In this paper, the results of tribological, microscopic and mechanical research of Al2O3 and Al2O3 + 40 wt.% TiO2 coatings manufactured by atmospheric plasma spraying (APS) were presented. The feedstock materials were Al2O3 (Metco 6103, Oerlikon Metco) and Al2O3 + 40 wt.% TiO2 (Metco 131VF, Oerlikon Metco) powders with the average grain size of 30 μm. The stainless steel (X5CrNi18-10) coupons had a diameter equal to 25 mm and 2 mm of thickness. The morphology and microstructure of obtained coatings were tested by scanning electron microscope (SEM). Then adhesion tests and tribological examinations by ball-on-disc (BoD) mode in technical dry friction conditions were carried out. During BoD testing, the load of 5 N was used. It was concluded that the Al2O3 coating was characterized by higher wear resistance and microhardness, but, at the same time, it was of lower fracture toughness than the Al2O3 + 40 wt.% TiO2 coating.