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2 results on '"Tests and analysis"'

1. Benchtop Spreadability Measurement of Powder

Author

Hulme-Smith, Christopher, Hari, Vignesh, Mellin, P., Hulme-Smith, Christopher, Hari, Vignesh, and Mellin, P.

Abstract

The behaviour of metal powders when they are spread into thin layers is critical for powder bed additive manufacturing and other processes. However, there is no accepted test procedure to quantify this behaviour. There is not even an accepted metric that can be used to assess this property. This increases the difficulty of developing new powders for additive manufacturing. The current study proposes test and analysis procedures that minimise the influence of operators and are aimed at providing maximum repeatability and reproducibility while minimising the need for specialist analysis equipment. Initial testing shows that a powder with good flow properties behaves as expected as a function of recoater speeds and always exhibits superior spread metrics to powders with poor flow properties. This provides an important step towards the establishment of a robust, inexpensive test that can help additive manufacturing to grow in new industries., QC 20220613

Published
2020

2. The effects of graphite, coke and ZnS on the tribological and surface characteristics of automotive brake friction materials

Author

Nurettin Yavuz, Rukiye Ertan, Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü., Ertan, Rukiye, and Yavuz, Nurettin

Subjects
Brake friction materials, Tribology, SB2S3, Scanning electron microscope, Brake lining, Braking systems, Performance, Friction surfaces, Engineering, Effect of temperature, Non-asbestos, Wear, Braking system, Brake, Automotive brake, Tests and analysis, Graphite, Composite material, Coefficient of friction, Brake performance, Lubricants, Friction Materials, Brake Linings, Pad, Energy dispersive x-ray, Friction coefficients, Coke, Friction layers, Friction testers, Physical properties of materials, Friction materials, Positive effects, Surfaces, Coatings and Films, Surfaces, Tribological properties, General Energy, Scanning electron microscopy, Materials science, Friction, Engineering, mechanical, Solid lubricants, Brake linings, Zinc sulfide, MOS2, Dry lubricant, Mechanical Engineering, Wear behaviors, Worn surface, Surface characteristics, Materials properties, Coefficient of frictions
Abstract

Purpose - The purpose of this paper is to investigate the role of solid lubricants (graphite, coke, ZnS) on brake performance. Design/methodology/approach - In this study, the tribological and surface characteristic of non-asbestos organic type brake friction materials containing three different solid lubricants (graphite, coke, and ZnS) in different proportions were examined and evaluated experimentally. The coefficient of friction (COF) and wear behavior of the samples were tested on a chase-type friction tester, and particular emphases were given to the effect of temperature and number of braking cycles on the COF. Each of the lubricants was added to the mixtures in different amounts and seven different brake linings were manufactured, provided that the total amount of solid lubricants and other ingredients were not changed. The worn surfaces of the specimens were analyzed using a scanning electron microscope with energy-dispersive X-ray microanalysis. Findings - The experimental results indicate that graphite has a positive effect on the tribological properties of brake linings. However, brake linings containing higher concentrations of ZnS and coke showed an unstable friction coefficient relationship with the temperature and number of braking cycles. The formation of friction layers was detected on the friction surface of these samples, which indicates that an increase in coke and ZnS content increases the discontinuous and unstable friction film areas. Originality/value - This paper fulfils the effects of solid lubricants (graphite, coke, ZnS) in brake friction materials with detailed tests and analysis.

Published
2011
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