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The purpose of this paper is to examine the practicability of the self-designed ambient humidity controllable pin-disc/rolling multifunctional friction and wear test device and to evaluate the friction and wear characteristics of materials under diverse ambient humidity conditions in different contact forms.

The practicability of the self-designed multifunctional friction tester was examined by the friction and wear tests of materials under different ambient humidity conditions [65%RH, 98%RH (relative humidity)] in diverse contact forms (pin/disc and rolling). Meanwhile, the friction and wear properties of pin/disc samples also rolling samples were assessed from three aspects: average friction coefficient, wear mass and wear morphology.

The results prove that the self-designed multifunctional friction tester has practicability. Therefore, it can be used to simulate the friction and wear tests of materials under diverse ambient humidity conditions in different contact forms. Besides, it is evident that the wear damage of pin/disc and rolling samples are greatly improved under high ambient humidity conditions. And when other conditions are identical, the higher the ambient humidity, the smaller the average friction coefficient, wear mass and wear damage degree of pin/disc also rolling samples.

This paper offers a self-designed multifunctional friction and wear test device. And the tester not only can realize the control of test ambient humidity, but also achieve the wear test of pin/disc or rolling contact forms. The design and production of the tester can offer convenience for the research of tribology, and provide fundamental guidance for the study of materials under high humidity condition in diverse contact forms.

The purpose of this paper is to find the influence of the initial braking velocity and braking frequency on the tribological performance of the non‐asbestos brake shoe used in mine hoisters during some continuous emergency brakings.

The tribological performance experiments of the WSM‐3 non‐asbestos brake shoe braking on the 16 Mn steel are investigated on the X‐DM friction tester, by simulating continuous emergency brakings of a mine hoister ten times. Three kinds of tribological indexes: friction coefficient, its stability coefficient, and wearing rate are considered to score the tribological performance of the brake shoe.

When the initial braking velocity increases, the mean friction coefficient of the brake shoe decreases at first, then rises, and falls again finally. But when the braking frequency exceeds seven times, the falling process of the friction coefficient at low‐velocity period does not appear again. Second, when the initial braking velocity is no higher than 10 m/s, the mean friction coefficient rises with the braking frequency increasing. But when the velocity exceeds 10 m/s, the mean friction coefficient rises with the braking frequency increasing at first, then falls. Third, when the initial braking velocity is no higher than 12.5 m/s, the friction coefficient of the brake shoe has quite a favorable stability with the coefficient is no bigger than 75 percent. But when the velocity exceeds 12.5 m/s, the stability of the friction coefficient is diminishing obviously. Fourth, the wearing rate of the brake shoe increases quickly, during the process that the velocity rising from 10 to 12.5 m/s, but increases much more slowly after that period.

The paper investigates the tribological performance of the WSM‐3 non‐asbestos brake shoe during some continuous emergency brakings and finds that, when the initial braking velocity is no higher than 12.5 m/s and the braking frequency is no more than seven times, the WSM‐3 non‐asbestos brake shoe has quite a high friction coefficient, a good friction stability, and a low‐wearing rate, which indicate that it is very appropriate for using in the disk brake of mine hoisters in China.

The purpose of this paper is to find the variations of brake lining's frictional performance with braking conditions, and their influence on the braking safety and reliability of automobiles.

As the semimetal brake lining is widely used currently in automobiles, it was selected as the experimental material. By simulating the braking conditions and environment of automobiles, some tribological experiments of the brake lining were investigated on the X‐DM friction tester, when it is paired with the friction disc made of gray cast iron. The influence of braking pressure, sliding velocity and surface temperature on the friction coefficient and its stability coefficient were studied in depth through experiments.

The friction coefficient decreases gradually with the increasing of braking pressure and sliding velocity when the surface temperature is naturally rising. It rises first then falls with the surface temperature rising and the maximal value appears at nearly 200°C. The stability of friction coefficient decreases obviously when the sliding velocity exceeds 30 m/s, the braking pressure exceeds 1.8 MPa and the surface temperature is over 200°C. Based on the experimental results, the authors consider that it is not reliable to execute an emergency braking only by rising the braking pressure when the automobile is driving with a high velocity. In order to reduce the bad influence of high temperature on frictional performance, some effective actions should be taken for cooling the friction disc. What is more, special attention should be paid to the decreasing of frictional stability during the braking with high velocity, pressure and temperature.

This paper studies the influence of braking conditions on friction coefficient and its stability of the semimetal brake lining for automobiles. It is believed that this research may have some actual guidance for enhancing the braking safety and reliability of automobiles.

The purpose of this paper is to improve the properties of metal nanoparticles which are easy to agglomerate and hard to disperse evenly, thus limiting the application of metal nanoparticles in grease. A novel technology was proposed for modifying metal oxide to improve the dispersibility of nanoparticles.

SA-TiO2 nanoparticles were synthesized using an in-situ esterification method followed by surface modification with stearic acid. The microstructure of the nanoparticles was characterized by scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy and their thermal stability was evaluated by thermogravimetric analyzer. The tribological properties of the SA-TiO2 nanoparticles as additives in lithium grease were evaluated with a four-ball tester and TE77 reciprocating friction tester. The worn surfaces of the steel balls were investigated by EDS and XPS.

The prepared nanoparticles can be well dispersed in the lithium grease and possess much better tribological properties compared to traditional nanoparticles. The results indicated that the excellent tribological performance of SA-TiO2 was attributed to the chemical reaction film composing of Fe2O3, iron oxide and other organic compounds.

This paper provides a method to prevent the agglomeration of nano-TiO2 by surface modification with stearic acid. And the prepared nanoparticles can effectively improve the tribology performance of lithium grease.

The purpose of this paper, brake friction material samples with six different contents were produced using three different fiber types consisting of variable proportions of huntite mineral and basalt, glass and steel fibers. The friction properties and formation of the transfer film in these friction materials were investigated.

Friction materials were produced using a hot molding method from materials containing 10%–15% huntite in varying proportions, consisting of basalt, glass and steel fibers. The densities and hardness values of the samples were measured. Friction tests were performed using a brake pad friction material tester to determine tribological properties. After the friction tests, microscopic examination of the sample surfaces was performed using scanning electron microscope (SEM) and three-dimensional (3D) surface profilometer devices.

Huntite mineral content and fiber type affected the friction coefficient. With an increase in the amount of huntite, the friction coefficient increased in the friction material samples formed with glass and steel fibers. The fiber type and amount of huntite also affected the transfer film formation. The surface roughness values of all the friction materials decreased with an increase in the amount of huntite. The surface roughness values of the samples with glass fibers were higher than those of other samples.

The importance of using huntite minerals and different fiber types in automotive brake friction materials is emphasized. This will help industrial companies and academics study the tribological properties of friction materials.

The effect of the load on the tribological properties of Si₃N₄-hBN sliding against Si₃N₄ were investigated under dry and water lubrication condition.

Using a MMU-5G type pin-on-disc friction and wear tester.

Under the dry friction, the wear mechanism was dominated by ploughing and abrasive wear, and the contact status was elastic contact under the load less than 25 N. With the increase of the load, the friction coefficient decreased; the main wear mechanism was fatigue fracture, and the contact status turned into plastic contact. Under water lubrication, effective lubrication film could be produced on the worn surface, and it had a function of fluid lubrication under the load less than 15 N. With the increase of the load, the pin and the disc came into direct contact, and the friction and wear of the pairs were aggravated; the wear mechanism changed from chemical wear into abrasive wear and brittle spalling.

The study on the effect of the load on the tribological properties of Si₃N₄-hBN sliding against Si₃N₄ was investigated under dry and water lubrication condition in the way of contact stress.

Kelp is widely productive and inexpensive. The purpose of this study is to explore kelp liquid (KL) as an environment-friendly water-based lubricant, which is expected to replace some industrial lubricants and protect the environment while satisfying lubricating performance.

In this experiment, the soaked kelp was broken up by a wall-breaking machine to get the KL by a centrifuge. Elements and crystal structure of KL samples were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and Raman spectra. The friction test is carried out by the relative movement of the polyethylene ball and the aluminum disk on the friction tester.

Friction experiments showed that 0.1 Wt.% KL has a good lubrication effect, and the average coefficient of friction is 0.063 under the condition of applying a 10 N load and moving at a speed of 2.0 cm/s. KL has good thermal conductivity with excellent cooling effect and high intermolecular force which makes high viscosity for excellent lubricating behavior, at the meantime molecules in solution remain stable which shows an excellent dispersibility.

At present, the research on kelp mainly focuses on its medicinal value and abundant nutritional value, and the research on its lubrication effect is less. Based on this situation, this paper explored the characteristics of KL as an environmentally friendly lubricant, which is expected to be used as a green cutting fluid.

The purpose of this paper is to investigate the tribological performance and mechanisms of BN/calcium borate nanocomposites (BCBNs) as additives in lubricating oil.

BCBNs were prepared by heterogeneous deposition method. And the morphology and structure of samples were analysed by transmission electron microscopy, Fourier transform infrared spectra and X-ray powder diffraction pattern. The maximum non-seizure load (PB) of samples was tested using four-ball friction tester. The average friction coefficients and wear tracks were obtained. In addition, tribological mechanism was also investigated using optical microscope, energy dispersive spectroscopy and X-ray photoelectron spectroscope.

It was found that the nanocomposites present core-shell nanostructure with the thickness of shell around 12 nm and the diameter of particles 100-200 nm, and tribological tests indicate that the PB value of BCBNs was increased by 113 per cent, whereas the average friction coefficient was decreased by 23.6 per cent and the bloom’s wear area was also decreased by 25.2 per cent.

This paper involves investigation on tribological properties and mechanism of the BCBNs with core-shell structure.

The purpose of this paper is to study the antirust, tribological performance and anti-wear (AW) mechanism of the of soybean lecithin (SL) as a kind of multifunctional lubricant additive.

As a kind of multifunctional lubricant additive, the antirust performance of SL was tested according to ASTM D 665, and meanwhile, its tribological performances were also evaluated by Optimol SRV-I oscillating reciprocating friction and wear tester and four ball tester. The worn steel surfaces were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS).

The results showed that the SL exhibited excellent antirust properties in different base stock, and could effectively improve the AW and extreme pressure (EP) performances. The results of SEM and XPS indicated that a protective film was formed between steel-steel friction pair during the tribological test.

This paper first investigated the antirust properties and the tribological mechanism of the SL as a kind of multifunctional lubricant additive, which can be very useful and will promote the application of SL in lubricant industry.

Ultra-high molecular weight polyethylene (UHMWPE) is adopted in water-lubricated bearings for its excellent performance. This paper aims to investigate the tribological properties of UHMWPE with a molecular weight of 10.2 million (g mol^‐1) under different molding temperatures.

The UHMWPE samples were prepared by mold pressing under constant pressure and different molding temperatures (140°C, 160°C, 180°C, 200°C, 220°C). The friction and wear tests in water were conducted at the RTEC tribo-tester.

The friction coefficient and wear loss decreased first and rose later with the increasing molding temperature. The minimums of the friction coefficient and wear loss were found at the molding temperatures of 200°C. At low melting temperatures, the UHMWPE molecular chains could not unwrap thoroughly, leading to greater abrasive wear. On the other hand, high melting temperatures will cause the UHMWPE molecular chains to break up and decompose. The optimal molding temperatures for UHMWPE were found to be 200°C.

Findings are of great significance for the design of water-lubricated UHMWPE bearings.