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Publication date: 9 January 2017

Gökhan Kara, Gencaga Purcek and Harun Yanar

The purpose of this paper is to achieve a hard and protective borided layer on commercially pure Ti (grade-2) by applying boriding, and to investigate the changes in its…

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Abstract

Purpose

The purpose of this paper is to achieve a hard and protective borided layer on commercially pure Ti (grade-2) by applying boriding, and to investigate the changes in its microstructure, hardness, friction and wear behaviors.

Design/methodology/approach

Pack boriding technique was used to form a hard boron diffusion layer on titanium substrate. A powder mixture of amorphous boron and anhydrous borax was used as a solid-state boriding media, and then the boriding was carried out under inert atmosphere.

Findings

A thick dual boride layer consisting of a monolithic titanium diboride (TiB2) on the top and titanium monoboride (TiB) whiskers beneath that layer formed at relatively low diffusion temperature under pressured inert argon atmosphere in a boriding media containing boron source and activator. With boriding at specified conditions, very hard (4100 Hv0.01) and thick monolithic TiB2 layer formed on the top-most layer which is required for improved tribological applications. Hardness decreased gradually through the TiB whisker layer and finally reached to the hardness of base material.

Originality/value

This paper investigates the effects of components of boriding mixture and conditions of thermal treatment on the formation of borided layer and its properties. In previous studies, boriding mixtures containing a boron source, an activator and a filler material was generally used at high temperatures around or above 1,050°C to achieve a thick monolithic layer on the top of the surface of titanium. In the present study, no filler material was used to accelerate the boron diffusion because filler materials may inhibit the diffusion of boron atom through the surface of substrate of titanium. Also, diffusion treatment was carried out under pressurized argon atmosphere at relatively low diffusion temperature to achieve boride layer with the improved hardness and durability.

Details

Industrial Lubrication and Tribology, vol. 69 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 16 October 2018

Harun Yanar, Hasan Huseyin Ayar, Muhammet Demirtas and Gencaga Purcek

This paper aims to investigate the effect of straight phenolic resin content on the fade behavior, frictions and wear characteristics of pre-determined brake pad composite matrix…

559

Abstract

Purpose

This paper aims to investigate the effect of straight phenolic resin content on the fade behavior, frictions and wear characteristics of pre-determined brake pad composite matrix having specific amount of barite (BaSO4), rock wool, Kevlar, graphite and magnetite.

Design/methodology/approach

Different amount of resin ranging between 16 and 20 wt. per cent were added by changing only the filler (barite) content of composite matrix. Subsequently, friction and wear behavior of the composite samples were analyzed using a special pin-on-disc type test system developed for brake pad sample. The worn surfaces were investigated by SEM and three-dimensional (3D) surface profilometer.

Findings

The average coefficient of friction (CoF) of composite samples and temperature of the disc surface showed a linear increase with decreasing the resin content. The sample having 20 wt. per cent resin showed the minimum wear rate with smooth worn surface. But the amount of fade is quite high in that sample. Decreasing resin content decreased the fade formation, and the composite with 16 per cent resin brought about the minimum fade formation. As the fade formation is unwanted in brake pad applications, the composite with 16 wt. per cent resin was proposed as the most appropriate one considering the performance parameters related to friction and wear.

Originality/value

This paper optimizes the resin content of composite brake pad materials to achieve the best combination of its tribo-performance and mechanical properties and provides valuable information for scientists and engineers working in that area.

Details

Industrial Lubrication and Tribology, vol. 72 no. 2
Type: Research Article
ISSN: 0036-8792

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