A review of the influence of environmental humidity and water on friction, lubrication and wear

The influence of graphite content on the dry sliding wear characteristics of Al6061/Gr composites along with Al6061/30SiC/Gr hybrid composites has been assessed using a pin-on-disc wear test. The composites with different volume fraction of graphite particles up to 13% were processed by in situ powder metallurgy (IPM) technique. The porosity and hardness of the resultant composites were also examined. It was found that an increase in the graphite content reduced the porosity, hardness, and friction coefficient of both types of composites. The hybrid composites were more porous and exhibited higher hardness and lower coefficient of friction at identical graphite contents. The increased graphite content in the range of 0–13 vol.% resulted in increased wear rate of Al/Gr composites. The Al/30SiC composite exhibited a lower wear rate as compared with the base alloy and graphite addition up to 9 vol.% improved the wear resistance of these hybrid composites. However, more graphite particles addition resulted in increased wear rate. SEM micrographs revealed that the wear mechanism was changed from mostly adhesive in the base alloy sample (Al/0Gr) to the prominently abrasive and delamination wear for Al/Gr and Al/SiC/Gr/composites.

Effect of the Graphite Content on the Tribological Behavior of Al/Gr and Al/30SiC/Gr Composites Processed by In Situ Powder Metallurgy (IPM) Method

In order to predict wear and eventually the life-span of complex mechanical systems, several hundred thousand operating cycles have to be simulated. Therefore, a finite element (FE) post-processor is the optimum choice, considering the computational expense. A wear simulation approach based on Archard's wear law is implemented in an FE post-processor that works in association with a commercial FE package, ABAQUS, for solving the general deformable–deformable contact problem. Local wear is computed and then integrated over the sliding distance using the Euler integration scheme. The wear simulation tool works in a loop and performs a series of static FE-simulations with updated surface geometries to get a realistic contact pressure distribution on the contacting surfaces. It will be demonstrated that this efficient approach can simulate wear on both two-dimensional and three-dimensional surface topologies. The wear on both the interacting surfaces is computed using the contact pressure distribution from a two-dimensional or three-dimensional simulation, depending on the case. After every wear step the geometry is re-meshed to correct the deformed mesh due to wear, thus ensuring a fairly uniform mesh for further processing. The importance and suitability of such a wear simulation tool will be enunciated in this paper.

http://iopscience.iop.org/article/10.1088/0965-0393/13/1/005/pdf

Finite element based simulation of dry sliding wear

The effect of annealing on the tribological and corrosion properties of Al–12Si samples produced by selective laser melting (SLM) is evaluated via sliding and fretting wear tests and weight loss experiments and compared to the corresponding material processed by conventional casting. Sliding wear shows that the as-prepared SLM material has the least wear rate compared to the cast and heat-treated SLM samples with abrasive wear as the major wear mechanism along with oxidation. Similar trend has also been observed for the fretting wear experiments, where the as-prepared SLM sample displays the minimum wear loss. On the other hand, the acidic corrosion behavior of the as-prepared SLM material as well as of the cast samples is similar and the corrosion rate is accelerated by increasing the heat treatment temperature. This behavior is due to the microstructural changes induced by the heat treatment, where the continuous network of Si characterizing the as-prepared SLM sample transforms to isolated Si particles in the heat-treated SLM specimens. This shows that both the wear and corrosion behaviors are strongly associated with the change in microstructure of the SLM samples due to the heat-treatment process, where the size of the hard Si particles increases, and their density decreases with increasing annealing temperature.

/pdf/tribological-and-corrosion-properties-of-al-12si-produced-by-7sf80p6va3.pdf

Tribological and corrosion properties of Al–12Si produced by selective laser melting

Aluminum/graphite (Al/Gr) composites have been used as self-lubricating materials due to the superior lubricating effect of graphite during sliding. This paper summarizes various tribological aspects of self-lubricating aluminum composites. The influence of various factors such as (a) material factors, graphite size and volume fraction, and (b) mechanical factors, applied load and sliding speed on the tribological properties of self-lubricating aluminum composites, is discussed. Furthermore, the tribological properties of self-lubricating composites as a function of these parameters and the active wear mechanism involved in various systems are discussed. Bringing self-lubricating composites into different operating systems is a solution to reduce the use of external toxic petroleum-based lubricants in sliding contacts in a way to help the environment and reduce energy dissipation in industrial components for strategies toward sustainability and energy efficiency.

Influences of graphite reinforcement on the tribological properties of self-lubricating aluminum matrix composites for green tribology, sustainability, and energy efficiency—a review

Hozumi Goto

Papers

Effect of varying load on wear resistance of carbon steel under unlubricated conditions

The influence of oxygen and water vapour on the friction and wear of an aluminium alloy under fretting conditions

Wear mechanism of Al–Si alloy impregnated graphite composite under dry sliding

Effects of ultrasonic vibration on the wear characteristics of a carbon steel: Analysis of the wear mechanism

Improvement of wear resistance for carbon steel under unlubricated sliding and variable loading conditions