The tribological performance of W-DLC in solid–liquid lubrication system addivated with Cu nanoparticles

Judicious selection of additives having chemical and physical compatibility with the DLC films may help improving the triboligical properties and durability life of DLC-oil composite lubrication systems. In this study, Cu nanoparticles were added to PAO6 base oil to compose a solid-liquid composite lubrication system with W-DLC film. The effects of nanoparticle concentration, test temperature and applied load on tribological performance were systematically studied by a ball-on-disk friction test system. The tribological results illustrated that Cu nanoparticles could lower the coefficient of friction (COF) and dramatically reduce the wear rates of W-DLC films. The optimal tribological behavior was achieved for the 0.1 wt.% concentration under 30 ℃ and the applied load of 100 N. The test temperature and applied load were vital influencing factors of the solid–liquid lubrication system. The bearing effect and soft colloidal abrasive film of spherical Cu nanoparticle contributed to the excellent tribological performance of the composite lubrication system under mild test conditions, meanwhile, the local delamination of W-DLC film and oxidation were the main causes of the friction failure under harsh test conditions. With test temperature and applied loads increase the degree of graphitization of the W-DLC film increased. In conclusion, there are several pivotal factors affecting the tribological performance of solid–liquid lubrication systems, including the number of nanoparticles between rubbing contact area, graphitization of the worn W-DLC films, tribofilms on the worn ball specimens and oxidation formed in friction test, and the dominant factor is determined by the testing condition.

A Durable PVDF/PFOTES-SiO2 Superhydrophobic Coating on AZ31B Mg Alloy with Enhanced Abrasion Resistance Performance and Anti-Corrosion Properties

A simple and practical spray method is employed to prepare a PVDF/PFOTES-SiO2 superhydrophobic composite coating on the AZ31B Mg alloy substrate. The morphology, composition, and water contact angle (CA) were measured by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM) and contact angle measuring instrument. Hydrophilic nano-SiO2 is modified by PFOTES to obtain hydrophobicity. The influence of the mass of PFOTES-SiO2 to PVDF on the hydrophobic properties was studied. The wear resistance and stability of the composite coating have been investigated by immersion test, cross-cut adhesion test and friction test. Additionally, the corrosion resistance was measured by electrochemical workstation and salt spray corrosion test. The CA of PVDF/PFOTES-SiO2 coating is 161.3° and the sliding angle (SAs) is less than 2°. After 10× the sandpaper friction test, the superhydrophobic contact angle of the coating remained above 155°, and the sliding angle was less than 5°, which indicated that the prepared coating is a strong superhydrophobic coating with good wear resistance. The results of the electrochemical tests show that the superhydrophobic coating improved the anti-corrosion performance of Mg alloy, and the water contact angle is greater than 150° after 168 h salt spray corrosion test. Due to its excellent superhydrophobicity, wear resistance and anti-corrosion properties, the robust PVDF/PFOTES-SiO2 coating is considered to have great potential for future applications in the automotive and marine industries.

Effect of Ti3SiC2 Amount on Microstructure and Properties of TiAl Matrix Composites

The TiAl matrix composites were manufactured using spark plasma sintering under the conditions of 1100 °C/10 min/30 MPa. The effect of Ti3SiC2 amount on microstructure and properties of TiAl matrix composites was investigated. Ti3SiC2 was homogeneously distributed in the TiAl matrix, and it partly decomposed to form Ti5Si3 and TiC. The TiAl matrix with 30 wt.% of Ti3SiC2 exhibited the lowest friction coefficient and wear rate of 0.507 and 1.35´10-4 mm3N-1m-1 at room temperature and 0.423 and 0.21´10-4 mm3N-1m-1 at 550 °C, while the compression strength reached the maximum value of 1080 GPa at room temperature and 640 GPa at 550 °C, respectively. The hardness reached the value of 5.1 GPa. The TiAl matrix composites had a lower friction coefficient and wear rate at 550 °C than at room temperature. A Ti3SiC2 lubricating film was formed on the friction surface of the TiAl matrix composites after friction test at room temperature, while a Fe-Ti-Al-Si-oxide lubricating film was formed after friction test at 550 °C. The wear mechanisms of the TiAl matrix composites with the Ti3SiC2 addition were mainly abrasive wear and adhesive wear at room temperature and 550 °C, respectively.

Evaluation of Sulfides as Solid Lubricant: Lubricity of Compounded Sulfides

Sulfide was used as solid lubricant, and MoS2 was popular. It was used industry as powder shape. Sulfur as oil additive; ZDDP, MoTDC were also well known. These composites make tribofilm which prevent seizure, scoring and some tribological troubles. In this paper, sulfides were synthesized by powder metallurgy technics. In addition, these sulfides were mixed with bronze powders and sintered as cylindrical specimen. As a result of the friction test in the lubricated condition, tribofilm were covered with specimen surface. By XPS observation, sulfides and oxides were detected on the specimen surface. In the test, additive was not contained in the lubricant because PAO as base oil was adapted. However, sulfide in the specimen affect the making the tribofilm, especially when bornite (Cu5FeS4) was used.

Design, characterization, and performance analysis of Miscanthus fiber reinforced composite for brake application

This study deals with the development of new friction materials by incorporating Miscanthus fiber (5, 10, and 15 weight %, noted Mat1, Mat2, and Mat3, respectively). The friction materials were tested for their physical, mechanical, and microstructural properties as per international standard. The performance analysis was carried out using Chase friction test rig. Results revealed that the biomass is beneficial with good fade, wear resistance, and recovery characteristics, with the same trend of other natural fibers. Therefore, this natural ingredient proved to be useful in the development of brake friction material.

Effect of micro-textures on lubrication characteristics of spur gears under 3D line-contact EHL model

Purpose The purpose of this paper is to use a combination of numerical simulation and experiment to evaluate the performance of laser surface texturing (LST) in the field of gear lubrication, and to more accurately predict the lubrication characteristics of different surfaces. Design/methodology/approach The method used in this paper is developed on the basis of the deterministic solution of the three-dimensional (3D) mixed elasto-hydrodynamic lubrication (EHL) model and the model parameters are corrected by friction test. The film pressure, film thickness and friction coefficient of different micro-textured tooth surfaces are predicted on the basis of accurate 3D mixed EHL models. Findings The results demonstrate that the micro-texture structure of the tooth surface can increase the local film thickness and enhance the lubricating performance of the tooth surface without drastically reducing the contact fatigue life. The stress distribution and friction characteristics of the tooth surface can be optimized by adjusting the micro-texture arrangement and the size of the micro-textures. Originality/value A new evaluation method using a 3D hybrid EHL model and friction test to predict the lubrication characteristics of LST is proposed, which can effectively improve the processing economy and save time. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2020-0423

Wear Characteristics Optimization of Al6061-Sugarcane Bagasse Ash Metal Matrix Composite Using Taguchi Method

In present work, Aluminium 6061 was reinforced by varying the percentage of sugarcanebagasse ash (SCBA). Al-SCBA composite samples were fabricated by stir casting method. The weartest conducted on the samples using a pin on disc machine under the normal sliding condition. Basedon the testing parameters (Volume fraction ‘V’, Load ‘L’, sliding speed ‘S’) an L27 Orthogonal arraydesign was selected. According to L27 array, the wear & friction test was conducted. variance analysis(ANOVA) was performed to find out the important parameter and contribution in percentage for eachparameter on the composite material. To verify the analysis results with experimented resultconfirmation test was carried out. Further, to find the wear mechanism on the composite sampleselectron microscopy (SEM) test was used.

Temperature induced friction increase in friction test and forming demonstrator for sheet metal forming

High process stability is needed in sheet metal forming industry. This can be achieved by predicting and controlling the transient process and temperature variation, especially at start of production. In this connection, the temperature induced friction changing plays a significant role because it leads to product failures. The handling of the transient friction effects is currently done reactively, based on the individual experience of the machine operators. In future, those transient effects need to be controlled. This paper shows initially an analysis of the temperature induced friction increase in a well-known and proven flat strip drawing test. Different tribological systems were tested at tool temperatures between 20 and 80 °C. The temperature increase results in a higher friction of up to 77 %. Several influences on friction increase will be presented. These friction influences were verified afterwards with a heated forming demonstrator under laboratory conditions.

Simultaneous energy harvesting and tribological property improvement

In this study, piezoelectric elements were added to a reciprocating friction test bench to harvest friction-induced vibration energy. Parameters such as vibration acceleration, noise, and voltage signals of the system were measured and analyzed. The results show that the piezoelectric elements can not only collect vibration energy but also suppress friction-induced vibration noise (FIVN). Additionally, the wear of the friction interface was examined via optical microscopy (OM), scanning electron microscopy (SEM), and white-light interferometry (WLI). The results show that the surface wear state improved because of the reduction of FIVN. In order to analyze the experimental results in detail and explain them reasonably, the experimental phenomena were simulated numerically. Moreover, a simplified two-degree-of-freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects, dynamics, and tribological behaviors of the added piezoelectric elements to the original system.