The effect of different metallic counterface materials and different surface treatments on the wear and friction of polyamide 66 and its composite in rolling-sliding contact

Original article can be found at: http://www.sciencedirect.com/science/journal/00431648 Copyright Elsevier B. V. DOI: 10.1016/S0043-1648(03)00054-1The effect of different metallic counterface materials and different surface treatments on the tribological behaviour of polymer and polymer composite under unlubricated, non-conformal and rolling-sliding contact has been investigated. The most widely used polymer materials - unreinforced polyamide 66 and its composite (RFL4036) – were tested. The metallic materials include aluminium, brass and steel and the surface treatments include Tufftride** treated (known as nitrocarbonising) and magnesium phosphate treated, etc. Tests were conducted over a range of slip ratios at a fixed load of 300 N, 1000 rpm rotational speed using a twin-disc test rig. The experimental results showed that the polyamide composite exhibited less friction and wear than the unreinforced polyamide 66 when running against steel and aluminium counterfaces. However, when tested against brass, polyamide 66 exhibited lower wear than the composite. The surface treatment of steel has a significant effect on the coefficient of friction and the wear rate, as well as on the tribological mechanism, of polyamide 66 composites. It has been observed that a thin film on the contact surface plays a dominant role in reducing the wear and friction of the composite and in suppressing the transverse cracks. This study clearly indicates that both the characteristics of the different counterface metallic materials and the surface treatment greatly control the wear behaviour of polyamide 66 and its composite.Peer reviewe

Correlation of dent depth to maximum contact force and damage of composite laminates

This document is the Accepted Manuscript version of the following article: Z. Shen, Y. G. Xu, and Andreas Chrysanthou, 'Correlation of Dent Depth to Maximum Contact Force and Damage of Composite Laminates', Key Engineering Materials, Vol. 627, pp. 353-356, 2014. The Version of Record is available online at doi: 10.408/www.scientific.net/KEM.627.353. © 2015 Trans Tec Publications, SwitzerlandA major concern affecting the efficient use of carbon fibre reinforced composite laminates in the aerospace industry is the low velocity impact damage which may be introduced accidentally during manufacture, operation or maintenance of the composite structures. It is widely reported that the contact behavior of composite laminates under low-velocity impact can be obtained under quasi-static loading conditions. This paper focuses on the study of the correlation of the dent depth to the maximum contact force and damage of composite laminates under quasi-static loading. Analytical and finite element simulation approaches were employed to investigate relations between the contact force and the dent depth. Experimental investigations on the correlation between dent depth, maximum contact force and damage include quasi-static indentation testing, optical and scanning electron microscopic examination of the damage under different loading levels. The effect of damage initiation and growth on the contact behaviour has been discussed. Results show that consistent correlations between the dent depth, maximum contact force and damage exist and can be predicted with the analytical and numerical approaches. Dent depth can be used as an engineering parameter in assessing the severity of damage for composite structures that are subjected to low-velocity impact. This may lead to the development of a cost-effective technique for the inspection and maintenance of composite structures in aerospace applications.Peer reviewe

Porosity control of in situ forming tungsten carbide in laser additive manufacturing (LAM)

© 2020 Old City Publishing, Inc. Published by license under the OCP Science imprint, a member of the Old City Publishing Group.The effect of powder compression on the formation of porosity when heating with a laser beam has been investigated. The starting materials were elemental powders of Fe, W and C which were locally melted to form WC in Fe matrix by an in situ laser additive manufacturing (LAM) process. The resulting microstructures have been studied and chemical analysis has been performed. The main application for the process is for the production of WC based or carbide cutting tooling by very accurate deposition of hard-facing materials onto a steel substrate. Fe is used as the matrix material since ferrous alloys are employed as the substrate for these applications.Peer reviewe

Arginine/Nanocellulose membranes for carbon capture applications

The present study investigates the influence of the addition of L-arginine to a matrix of carboxymethylated nanofibrillated cellulose (CMC-NFC), with the aim of fabricating a mobile carrier facilitated transport membrane for the separation of CO2. Self-standing films were prepared by casting an aqueous suspension containing different amounts of amino acid (15\u201330\u201345 wt.%) and CMC-NFC. The permeation properties were assessed in humid conditions (70\u201398% relative humidity (RH)) at 35 \ub0C for CO2 and N2 separately and compared with that of the non-loaded nanocellulose films. Both permeability and ideal selectivity appeared to be improved by the addition of L-arginine, especially when high amino-acid loadings were considered. A seven-fold increment in carbon dioxide permeability was observed between pure CMC-NFC and the 45 wt.% blend (from 29 to 220 Barrer at 94% RH), also paired to a significant increase of ideal selectivity (from 56 to 185). Interestingly, while improving the separation performance, water sorption was not substantially affected by the addition of amino acid, thus confirming that the increased permeability was not related simply to membrane swelling. Overall, the addition of aminated mobile carriers appeared to provide enhanced performances, advancing the state of the art for nanocellulose-based gas separation membranes

Chord line force versus displacement for thin shallow arc pre-curved bimetallic strip

This is the accepted version of the following article: G D Angel, G Haritos, A Chrysanthou & V Voloshin, “Chord line force versus displacement for thin shallow arc pre-curved bimetallic strip”, Journal of Mechanical Engineering Science, Vol. 229(1): 116-124, first published online April 29, 2014, published by SAGE Publishing. All rights reserved. The version of record is available online at doi: http://dx.doi.org/10.1177/0954406214530873A pre-curved bimetallic strip that is applied with a force in an axial orientation, i.e. along its chord line, exhibits nonlinear force-displacement characteristics. For thin bimetallic strips, whereby the radius of curvature is large compared to the thickness of the strip, the non-linearity tends to be tangent related. The new theoretical formula introduced here was correlated to the results of a set of force-displacement tests, and a good overall fit of the theory to the test data was achieved. The formula put forward in this work enables the evaluation of large chord line displacements but is limited to the permissible stress limits of the material. This work can also be directly applied to thin shallow arc beams of a single material. The application of this work is in the field of bimetallic force-displacement actuators.Peer reviewe

Effect of pulsed electric current treatment on corrosion of structural metals

Results of corrosion tests of some structure metals previously treated using pulsed electric current of high density are presented. According to the data obtained, the treatment substantially affects corrosion of metals. In cases of HSLA steel and 5182 aluminum alloy, an increase of corrosion resistance occurs, whereas the same treatment causes a dramatic reduction of corrosion resistance of 5754 aluminum alloy.Наведено результати випробувань на корозію ряду конструкційних матеріалів, що попередньо зазнавали впливу імпульсного електричного струму високої густини. Установлено, що така обробка суттєво впливає на корозію матеріалів. Для сталі HSLA й алюмінієвого сплаву 5182 має місце зростання\ud опору корозії, в той час як для алюмінієвого сплаву 5754 - різке зменшення опору корозії.Представлены результаты испытаний на коррозию ряда конструкционных материалов, предварительно подвергаемых воздействию импульсного электрического тока высокой плотности. Установлено, что такая обработка существенно влияет на коррозию исследуемых материалов. Для стали HSLA и алюминиевого сплава 5182 происходит рост сопротивления коррозии, в то время как для алюминиевого сплава 5754 - резкое уменьшение сопротивления коррозии

Effect of electropulsing on the fatigue resistance of aluminium alloy 2014-T6

The effects of electropulsing on the fatigue resistance of aluminium alloy 2014-T6 were studied in relation to electric current amplitude, pulse duration, and number of repetitions. Utilising the Taguchi method, the present study identified the current amplitude and the duration of the electropulsing as the two critical treatment parameters for improved fatigue resistance. A 97% fatigue life improvement was achieved under the electropulsing conditions that were applied. An increase in microhardness and a decrease in electrical conductivity due to electropulsing were correlated with enhanced fatigue resistance in the alloy. Mechanisms related to the effects of the electropulsing treatment were elucidated based on observations from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) as well as numerical simulation results. The mechanisms identified by observation included dislocation movement and the secondary precipitation of GP-zones. Further explication of these mechanisms was provided by the application of a “magnetic field’’ model

Effect of Alternating Magnetic Field on the Fatigue Behaviour of EN8 Steel and 2014-T6 Aluminium Alloy

The application of an alternating magnetic field (0.54 T) was observed to lead to an improvement in the fatigue endurance and an increase in Vickers microhardness and tensile strength of both EN8 steel and AA2014-T6 alloy. Fractography using scanning electron microscopy showed evidence of more ductile fracture features after treatment in contrast to untreated samples. The results of X-ray diffraction indicated formation of more compressive residual stresses following treatment; while examination by transmission electron microscopy showed evidence of fewer dislocations. In the case of the AA2014-T6 alloy; GP zones were also generated by the alternating magnetic field. However; the temperature increase during the treatment was too low to explain these observations. The results were attributed to the non-thermal effect of the alternating magnetic field treatment that led to depinning and movement of dislocations and secondary precipitation of copper

Novel glass-ceramic composition as sealant for SOFCs

This is the pre-peer reviewed version of the following article: Federico Smeacetto, Auristela De Miranda, Andreas Chrysanthou, Enrico Bernardo, Michele Secco, Massimiliano Bindi, Milena Salvo, Antonio G. Sabato, and Monica Ferraris, ‘Novel Glass‐Ceramic Composition as Sealant for SOFCs’, Journal of the American Ceramic Society, Vol. 97 (12): 3835-3842, December 2014, which has been published in final form at https://doi.org/10.1111/jace.13219. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This work deals with the design, the characterization, and testing of a novel glass-ceramic to be used as sealant for planar solid oxide fuel cells and its compatibility with Mn1.5Co1.5O4-coated Crofer22APU. Thermal, sintering, and crystallization behavior and thermo mechanical properties of the sealant are reviewed and discussed, indicating therefore that these compositions can be deposited at 850C and provide an excellent compatibility with both the Mn1.5Co1.5O4-coated Crofer22APU and the anode-supported electrolyte. In particular, Mn1.5Co1.5O4-coated Crofer22APU/sealant/anode-supported-electrolyte joined samples have been submitted to thermal tests (in air atmosphere) from RT to 800C (SOFC operating temperature) up to 500 h. No interactions, cracks formation, or failure were observed at the Mn1.5Co1.5O4-coated Crofer22APU/sealant interface and between the glass-ceramic and the anode-supported-electrolyte after 500 h of thermal tests in air atmosphere.Peer reviewe