Search results

Aluminium silicon carbide reinforced metal matrix composite (Al/SiC‐MMC) materials are rapidly replacing conventional materials in various automotive, aerospace and other industries. Accordingly, the need for accurate machining of composites has increased enormously. The present work analyzes the machining of Al/SiC composites for surface roughness. An empirical model has been developed to correlate the machining parameters and their interactions with surface roughness. Response surface regression and analysis of variance are used for making the model. The developed model can be effectively used to predict the surface roughness in machining Al/SiC‐MMC composites. The influences of different parameters in machining Al/SiC particulate composites have been analyzed through contour graphs and 3D plots.

The purpose of this study is to reveal the usability of waste paper sludge on the production of composite materials and the printability of their surfaces were investigated.

First, composite plates were produced by using dried and milled waste sludge together with polyester resin and epoxy. Screen printing using water, solvent and UV-based inks were carried out.

It was determined that UV and solvent-based inks in both resin groups were permanently attached to the surface of composite plates produced using paper mill waste sludge, while it was found that the adhesion was not achieved sufficiently in cardboard factory waste sludge.

The unique aspect of this study is obtained the composite plates from paper mill and cardboard mill waste sludge and improved the printability of them.

This paper aims to investigate the wear behaviors of aged metal matrix composites and of the as-cast Al-Si alloy by using a pin-on-disk wear testing machine at room temperature.

Hypoeutectic (Al-7Si) alloy reinforced with low volume fractions of SiC particles (SiC_p) and graphite (Gr) particles were prepared by the stir-casting process. It was found that the addition of 9 Wt.% of SiC_p and 3 Wt.% of Gr particles conferred a beneficial effect in reducing the wear rate of the composites.

The worn-out surfaces of the specimens were examined using scanning electron microscopy (SEM); the extensive micro cracking occurs on the surface of the Al-7Si alloy tested at lower loads. The growth of these microcracks finally led to the delamination of the base alloy surface. The reinforcements (SiCp and Gr) particles tended to reduce the extent of plastic deformation in the surface layer, thereby reducing extensively the occurrence of micro cracking in the composites.

From the results, it is revealed that the quantity of wear rate was less for aged specimens compared to the as-cast specimens. The worn-out surfaces were studied using electron dispersive spectroscopy, and wear debris was analyzed using SEM.

The effect of different service parameters on the current-carrying tribological properties of CF-Al₂O₃/Cu composites was investigated, and the damage behavior of the composites under different service parameters was probed. The purpose of this study is to provide a theoretical basis for the application of CF-Al₂O₃/Cu composites.

The composites were fabricated by internal oxidation combined with powder metallurgy. The current-carrying tribological properties of CF-Al₂O₃/Cu composites were investigated on an electrical damage test system at different loads and currents.

As the load increases, the wear mechanism of the composite changes from abrasive wear to delamination wear. As the current increases, the oxidation wear and arc erosion of the composites gradually intensified. Under the service parameters of 0–25 A and 30–40 N, the composite has relatively stable current-carrying tribological properties.

This paper could provide a theoretical basis for the practical application of CF-Al₂O₃/Cu composites.

The objective of the present investigation is to prepare a Zn–Al matrix (73 wt. per cent Zn + 27 wt. per cent Al) reinforced with SiC and graphite (Gr) hybrid composites by a rapid current sintering technique. Well-known Zn-based alloys are good candidates for load bearing applications. However, some limitations exist in Zn sublimation during casting and solid-state sintering and low-sliding velocity applications. The purpose is to develop new hybrid composites for self-lubricated bearing alloys by the facile production technique of current-activated sintering for these types of hybrid composites at very short sintering periods.

Designing a special power unit for current sintering. The hybrid composites of the Zn–Al matrix were reinforced with 20 vol. per cent SiC and different amounts of Gr (2.5, 5.0, 7.5 and 10 weight per cent) and sintered rapidly by current sintering. Tribological tests for wear behaviors and self-lubrication effect were studied. The authors' approach is mainly to produce low-cost load-bearing materials.

Successful and rapid production of Zn–Al alloy SiC/Gr hybrid composites in this study led to increasing load bearing capacity, decreasing friction coefficient and wear rate and production of good substitutes for conventional bearing applications.

A conventional Zn alloy was reinforced with both SiC and Gr particles. This work is original in two ways. It is noted after the literature survey that this alloy is first reinforced with two different types of reinforcements as a hybrid type of composite. Second, the consolidation of this hybrid material was carried out by a direct current for eliminating Zn sublimation and shortening the production time. In tribological applications demanding strength and lubrication requirements, Zn–Al/SiC/Gr hybrid composites were assessed as good substitutes for conventional materials owing to improved wear resistance as a result of combined reinforcement of SiC and Gr particulates.

The purpose of this paper is to investigate the distribution and surface characteristic of transfer film of polyamide composites filled with ZnOw during traction rolling.

In this paper, the traction rolling tribological behavior of polyamide composites filled with ZnOw was studied with a twin-disc traction rolling tester. The topography of transfer film was observed with a three dimensional profiler. Meantime the thickness of transfer film was measured. The chemistry elements of transfer film were analyzed with EDS and XRD.

The results indicated that transfer film of composites patchily covered on the surface of counter disc, the amount of which increased with increasing cycles. The coverage and thickness of pure PA film increased against rolling cycles. However, the thickness of 15 wt.% ZnOw/PA film remained at 6 μm as the coverage rose against rolling cycles. Fe element was found in pure PA transfer film, which existed in Fe0 and FeO for chemical reaction between Fe and atmospheric oxygen. Transfer film of 15 wt.% ZnOw/PA composites included a little Zn and Fe element. Fe element existed as Fe0. Zn element existed as ZnO.

This paper presented the distribution and surface characteristic of transfer film during traction rolling.

This paper aims to clarify the friction properties of 304 steel surface modification. The surface modification includes laser texturing processing and nitriding treatment on 304 steel surface, and then the friction properties’ test was conducted on different friction directions and different upper test samples by using microfriction and wear testing machine.

The diameter and spacing of 100-, 150-, 200-, 300-μm pit array on the surface of 304 steel were calculated using a M-DPSS-50 semiconductor laser device. Then, the textured surface was nitriding-treated using a nitriding salt bath device. The chemical composition, surface morphology and surface microhardness of the composite-modified surface were measured by X-ray diffraction and by using an optical microscope and a microhardness tester. The tribological characteristics of the composite-modified surface were tested by MRTR microcomputer-controlled multifunctional friction and wear testing machine.

The result showed that a rule pit texture surface was obtained by the texture processing. The microhardness of nitriding treatment surface reached 574.27HV0.1, which significantly higher than 222.58HV0.1 of 304 steel. The composite-modified surface has excellent anti-friction and wear resistance properties when the upper specimen was GCr15 steel and ZrO2, respectively. The composite-modified surface has excellent anti-friction and anti-wear properties after long time friction under different angles. However, the friction coefficient and wear morphology of the friction pairs are not affected by the friction angle.

Because of the chosen research approach, the research results may lack generalizability. Therefore, researchers are encouraged to test the proposed propositions further.

The paper conducted a systematic study of the tribological characteristics of 304 steel composite modification surface and provided a good basis for the extensive application of 304 steel.

The study provides a good basis for the extensive application of 304 steel.

This paper fulfils an identified need to study the extensive application of 304 steel.

This purpose of this study was to investigate the effects of carbon fiber (CF) and/or glass fiber (GF) fillers on the tribological behaviors of ultrahigh-molecular-weight polyethylene (UHMWPE) composites to develop a high-performance water-lubricated journal bearing material.

Tribological tests were conducted using a pin-on-disc tribometer using polished GCr15 steel pins against the UHMWPE composite discs under dry conditions with a contact pressure of 15 MPa and a sliding speed of 0.15 m/s. Scanning electron microscopy, laser 3D micro-imaging profile measurements and energy-dispersive X-ray spectrometry were used to analyze the morphologies and elemental distributions of the worn surfaces.

The results showed that hybrid CF and GF fillers effectively improved the wear resistance of the composites. The fiber fillers decreased the contact area, promoted transfer from the polymers and decreased the interlocking and plowing of material pairs, which contributed to the reduction of both the friction coefficient and the wear rate.

The UHMWPE composite containing 12.5 Wt.% CF and 12.5 Wt.% GF showed the best wear resistance of 2.61 × 10⁻⁵ mm³/(N·m) and the lower friction coefficient of 0.12 under heavy loading. In addition, the fillers changed the worn surface morphology and the wear mechanism of the composites.

Specific chemical environments step out in the industry objects. Portland cement composites (concrete and mortar) were impregnated by using the special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot were applied as the industrial waste. Portland cement composites were made of the same aggregate, cement and water. The durability of prepared cement composite samples was tested in 5 per cent solution of HCl and 5 per cent solution of H₂SO₄ as a function of immersion time. The changes in mechanical strength and mass of the samples were periodically measured. Cement composites impregnated with sulfur composite exhibited limited mechanical strength and mass loss, whereas physico-mechanical properties of Portland cement concrete regressed rapidly. The loss in weight of ordinary concrete impregnated with sulfur composite, kept in aqueous solutions of acids, hydroxides, salts and in water for a year was determined using 100 × 100 × 100 mm samples. The same samples were then used in compressive strength tests.

Specific chemical environments affect industrial objects. Portland cement composites (concrete and mortar) were impregnated with a special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot were applied as industrial waste. Portland cement composites were made of the same aggregate, cement and water. The durability of the prepared cement composite samples was tested in 5 per cent solution of HCl and 5 per cent solution of H₂SO₄ as a function of immersion time. The changes in mechanical strength and mass of the samples were periodically measured. Cement composites impregnated with sulfur composite exhibited limited mechanical strength and mass loss, whereas the physico-mechanical properties of the Portland cement concrete regressed rapidly. The loss in weight of ordinary concrete impregnated with sulfur composite, kept in aqueous solutions of acids, hydroxides, salts and in water for a year was determined using 100 × 100 × 100 mm samples. The same samples were then used in compressive strength tests. The image analysis used for surface destruction monitoring, performed by scanning microscopy for the determination of damaged surface area and the original surface area before acid resistance testing, showed similar results. Based on the image analysis results, a model for predicting the degradation of mechanical strength during durability testing was established. The fact that the calculated and experimental strength values were not vastly different proved the validity of the proposed model. A brief summary of new products related to the special sulfur composite is given as follows: impregnation, repair, overlays and precast polymer concrete will be presented. Sulfur composite as a polymer coating impregnation, which has received little attention in recent years, currently has some very interesting applications.

Author comments: The article is original. The article has been written by the stated authors who are all aware of its content and approve its submission. 3. The article has not been published previously. 4. The article is not under consideration for publication elsewhere. 5. No conflict of interest exists, or if such conflict exists, the exact nature must be declared. 6. If accepted, the article will not be published elsewhere in the same form, in any language, without the written consent of the publisher.

Author comments: 1. The article is original. 2. The article has been written by the stated authors who are all aware of its content and approve its submission. 3. The article has not been published previously. 4. The article is not under consideration for publication elsewhere. 5. No conflict of interest exists, or if such conflict exists, the exact nature must be declared. 6. If accepted, the article will not be published elsewhere in the same form, in any language, without the written consent of the publisher.

This paper aims to investigate the microstructure, hardness and tribological properties of hypoeutectic (Al-7Si) matrix reinforced with fixed quantities of 3 Wt.% graphite (Gr) and x Wt.% SiCp (x = 3, 6 and 9) hybrid composites.

The composites were fabricated by stir cast technique. The microstructure, hardness and tribological measurements were carried out on the base alloy and composites. The tribological investigation was carried out on pin-on-disc wear testing machine under dry sliding condition.

The wear rate decreases with the increase of SiCp into A356-3Gr composites. The composite containing A356-9SiCp-3Gr had better hardness and good wear resistance compared to the base alloy. Scanning electron microscope (SEM) and electro dispersive spectrometry (EDS) images were used to study the reinforcement distribution and worn-out surface of the specimens.

The present paper brings out a clear picture of the various events that take place under the worn-out surfaces leading to the generation of mechanical mixed layer.