The tribological properties and wear mechanism of copper coated graphite doped Sialon ceramic composites at wide range temperature from 25 to 800 °C

Transparent glass-ceramic composites embedded with Ln-fluoride nanocrystals are prepared in this work to enhance the upconversion luminescence of Tm3+. The crystalline phases, microstructures, and photoluminescence properties of samples are carefully investigated. KYb3F10 nanocrystals are proved to controllably precipitate in the glass-ceramics via the inducing of Yb3+ when the doping concentration varies from 0.5 to 1.5 mol%. Pure near-infrared upconversion emissions are observed and the emission intensities are enhanced in the glass-ceramics as compared to in the precursor glass due to the incorporation of Tm3+ into the KYb3F10 crystal structures via substitutions for Yb3+. Furthermore, KYb2F7 crystals are also nano-crystallized in the glass-ceramics when the Yb3+ concentration exceeds 2.0 mol%. The upconversion emission intensity of Tm3+ is further enhanced by seven times as Tm3+ enters the lattice sites of pure KYb2F7 nanocrystals. The designed glass ceramics provide efficient gain materials for optical applications in the biological transmission window. Moreover, the controllable nano-crystallization strategy induced by Yb3+ opens a new way for engineering a wide range of functional nanomaterials with effective incorporation of Ln3+ ions into fluoride crystal structures.

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Effect of High−Speed Powder Feeding on Microstructure and Tribological Properties of Fe−Based Coatings by Laser Cladding

Coatings ◽

10.3390/coatings11121456 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1456

Author(s):

Qiang Wang ◽

Runling Qian ◽

Ju Yang ◽

Wenjuan Niu ◽

Liucheng Zhou ◽

...

Keyword(s):

Wear Resistance ◽

Laser Cladding ◽

Tribological Properties ◽

Wear Mechanism ◽

High Speed ◽

High Efficiency ◽

Adhesive Wear ◽

Steel Substrate ◽

Powder Materials ◽

Powder Feeding

In order to improve the wear resistance of 27SiMn steel substrate, Fe−based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high−speed powder feeding (HF) process was used to prepare Fe−based alloy coating on 27SiMn steel substrate. The effect of diversified energy composition of powder materials on the microstructure and properties of coatings were systematically studied. X−ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the phase structure and microstructure of Fe−based alloy coatings, and the hardness and tribological properties were measured by the microhardness tester and ball on disc wear tester, respectively. The results show that the microstructure of conventional gravity feeding (GF) coatings was composed of coarse columnar crystals. In comparison, owing to the diversification of energy composition, the microstructure of the high−speed powder feeding (HF) coatings consists of uniform and small grains. The total energy of the HF process was 75.5% of that of the GF process, proving that high−efficiency cladding can be achieved at lower laser energy. The refinement of the microstructure is beneficial to improve the hardness and wear resistance of the coating, and the hardness of the HF coating increased by 9.4% and the wear loss decreased to 80.5%, compared with the GF coating. The wear surface of the HF coating suffered less damage, and the wear mechanism was slightly adhesive wear. In contrast, wear was more serious in the GF coating, and the wear mechanism was transformed into severe adhesive wear.

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Investigation of graphite effect on the mechanical and tribological properties of Al 7075-SiC-graphite hybrid metal matrix composites

Tribologia - Finnish Journal of Tribology ◽

10.30678/fjt.82667 ◽

2020 ◽

Vol 37 (1−2) ◽

Author(s):

SRIDHAR ATLA ◽

Prasanna Lakshmi Kaujala

Keyword(s):

Silicon Carbide ◽

Powder Metallurgy ◽

Tribological Properties ◽

Metal Matrix ◽

Ceramic Composites ◽

Wear Behaviour ◽

Wear Loss ◽

Mechanical And Tribological Properties ◽

Al 7075 ◽

Pin On Disc

The aluminium metal matrix composite reinforced with ceramic material of Silicon carbide (SiC) has good mechanical properties. However, aluminium based ceramic composites require improvements in their lubrication and tribological properties. In this study an attempt is made in the development of a new material through powder metallurgy technique by the addition of Graphite, which acts as a solid lubricant. This work investigated the inﬂuence of graphite on the wear behaviour of Al 7075/SiC /X wt.% graphite(X=0, 5 and 10) hybrid composite. The investigation reveals the effectiveness of incorporation of graphite in the composite for gaining wear reduction. The Al 7075 (aluminium alloy 7075) reinforced with SiC –graphite were investigated. The composites were fabricated using powder metallurgy route. The microstructures, material combination, wear and friction properties were analysed by scanning electron microscopy, XRD, and pin-on-disc wear tester. The newly developed aluminium composite has signiﬁcant improvements in tribological properties with a combination of 5% Silicon carbide (SiC) and 5% Graphite. The test reveals that sliding distance of 1000 m and sliding speed of 1.5 m/s with applied load of 5 N result in minimum wear loss of 0.01062g and coefficient of friction as 0.1278.

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Effect of graphene platelets on tribological properties of boron carbide ceramic composites

International Journal of Refractory Metals and Hard Materials ◽

10.1016/j.ijrmhm.2016.11.015 ◽

2017 ◽

Vol 65 ◽

pp. 57-63 ◽

Cited By ~ 27

Author(s):

Richard Sedlák ◽

Alexandra Kovalčíková ◽

Ján Balko ◽

Pawel Rutkowski ◽

Aleksandra Dubiel ◽

...

Keyword(s):

Boron Carbide ◽

Tribological Properties ◽

Ceramic Composites ◽

Graphene Platelets

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OPERATING CAPACITY OF ANTI-OXIDIZING COATING IN HYPERSONIC FLOWS OF AIR PLASMA

Surface Review and Letters ◽

10.1142/s0218625x18501457 ◽

2019 ◽

Vol 26 (02) ◽

pp. 1850145 ◽

Cited By ~ 2

Author(s):

ALEXEY N. ASTAPOV ◽

EKATERINA L. KUZNETSOVA ◽

LEV N. RABINSKIY

Keyword(s):

Oxide Film ◽

Ceramic Composites ◽

Hypersonic Flows ◽

Protective Film ◽

Air Plasma ◽

Main Layer ◽

Operating Capacity ◽

Heat Resistant ◽

Wide Range ◽

Erosion Loss

In this paper, we present the results of investigations of degradation processes that occur in the structure promising high-temperature anti-oxidizing of heat-resistant coating of the Si–TiSi2–MoSi2–B–Y system in hypersonic flows of air plasma. The coating is designed to protect a wide range of heat-resistant materials (carbon–carbon and carbon–ceramic composites, coal–graphite materials, alloys based on Nb, Mo, W, etc.). It is found that the coating operating capacity at surface temperatures [Formula: see text] 1820–1830∘C is provided by the structural-phase state of its microcomposite main layer and formation on the coating surface of a heterogeneous passivating protective film. It is based on borosilicate glass reinforced by rutile microneedles. The mechanism of coating destruction at [Formula: see text] 1850–1860∘C is erosion loss of oxide film as well as generation and growth of gas-filled cavities at the “coating main layer–oxide film” interface. As the pressure of saturated vapor of gaseous oxidation products (SiO, CO, MoO3 and B2O3) exceeds that of the ambient, the oxide film integrity is disrupted and oxidation process becomes active. The rates of erosion loss and sublimation grow as operating temperature increases and ambient pressure decreases.

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Preparation of high-performance PEEK anti-wear blends with melt-processable PTFE

High Performance Polymers ◽

10.1177/0954008319893741 ◽

2019 ◽

Vol 32 (6) ◽

pp. 645-654

Author(s):

Xiaotao Qiu ◽

Congli Fu ◽

Aiqun Gu ◽

Yang Gao ◽

Xiuli Wang ◽

...

Keyword(s):

Tensile Strength ◽

Wear Resistance ◽

Surface Analysis ◽

Tribological Properties ◽

High Performance ◽

Tribological Performance ◽

Mechanical And Tribological Properties ◽

The Past ◽

Wide Range ◽

Potential Applications

High-performance anti-wear polyetheretherketone/polytetrafluoroethylene (PEEK/PTFE) blends have drawn much attention over the past few years, owing to their wide range of potential applications. However, a convenient and effective method to prepare such blends with superior mechanical and tribological properties is still lacking. In this work, we propose a promising approach that uses melt-processable PTFE (MP PTFE), instead of conventional PTFE, to prepare anti-wear blends. MP PTFE, with melt flow abilities under appropriate conditions, can disperse homogeneously in PEEK, enhancing both the mechanical and tribological properties of the PEEK/PTFE blend. To prove this postulation, in this work, both MP PTFE and commercial PTFE were blended with PEEK, separately, and the effects of PTFE type and content on the tensile and tribological properties of the blends were studied. The results showed that, although the addition of commercial PTFE to PEEK could increase the wear resistance, it decreased the tensile strength of PEEK significantly. Compared to the blends with commercial PTFE, the blends with MP PTFE exhibited better tribological performance and higher tensile strength for PTFE content below 10 wt%. It was confirmed that the better dispersion of MP PTFE in PEEK endowed the blends with higher tensile strength. The surface analysis indicated that the MP PTFE could readily migrate to and enrich the surfaces of the blends. The relatively high PTFE content on the surface favored the formation of tribo-films, enhancing the tribological properties of the blends.

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Multi-Purpose Porous Ceramic Material

Materials Science Forum ◽

10.4028/www.scientific.net/msf.931.594 ◽

2018 ◽

Vol 931 ◽

pp. 594-597

Author(s):

Yu.S. Bagaiskov

Keyword(s):

Ceramic Material ◽

Construction Material ◽

Porous Ceramic ◽

Ceramic Composites ◽

Refractory Clay ◽

Treatment Processes ◽

Wide Range ◽

Porosity And Permeability ◽

And Performance ◽

Criteria For Evaluation

The main criteria for evaluation of ceramic products’ properties are strength, structural and mechanical, and thermophysical properties. To produce ceramic composites with a wide range of structural, mechanical, strength, and performance properties depending on application, various additives (flux agents, sintering agents, fillers) and heat treatment processes are used. Studies to determine a rational mixture composition have been carried out. A multipurpose material, comprising particles of the basic chamotte filler (burned clay) with a bonding agent in the form of refractory clay from the Latnenskoye deposit with a field spar fluxing agent, an additional filler made of heat-resistant silicon carbide, and an adhesive component in the form of powdered dextrin, is suggested. According to the combination of its ensured parameters, the obtained ceramic material can be multipurpose. Its degree of porosity and permeability make the material filtering, sound-proofing, and heat-retaining; considering the low density, it can be used as a lightweight construction material.

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