Search results

1 – 10 of over 1000
To view the access options for this content please click here
Article
Publication date: 8 January 2018

Yun He, Fanghong Sun and Xuelin Lei

This study aims to obtain diamond-coated mechanical seals with improved sealing performance and considerable cost. To achieve this purpose, the study focuses on depositing…

Abstract

Purpose

This study aims to obtain diamond-coated mechanical seals with improved sealing performance and considerable cost. To achieve this purpose, the study focuses on depositing uniform, wear-resistant and easily polished diamond coatings on massive mechanical seals in a large-scale vacuum chamber.

Design/methodology/approach

The computational fluid dynamics simulation test and its corresponding deposition experiment are carried out to improve the uniformity of diamond films on massive mechanical seals. The polishing properties and sealing performance of mechanical seals coated with three different diamond films (microcrystalline diamond [MCD], nanocrystalline diamond [NCD] and microcrystalline/nanocrystalline diamond [MNCD]) and uncoated mechanical seals are comparatively studied using the polishing tests and dynamic seal tests to obtain the optimized diamond coating type on the mechanical seals.

Findings

The substrate rotation and four gas outlets distribution are helpful for depositing uniform diamond coatings on massive mechanical seals. The MNCD-coated mechanical seal shows the advantages of high polishing efficiency in the initial polishing process and excellent wear resistance and self-lubrication property in the follow-up polishing period because of its unique composite diamond film structures. The MNCD-coated mechanical seal shows the longest working life under dry friction condition, about 14, 1.27 and 1.9 times of that for the uncoated, MCD and NCD coated mechanical seals, respectively.

Originality/value

The effect of substrate rotation and gas outlets distribution on temperature and gas flow field during diamond deposition procedure is simulated. The MNCD-coated mechanical seal exhibits a superior sealing performance compared with the MCD-coated, NCD-coated and uncoated mechanical seals, which is helpful for decreasing the operating system shut-down frequency and saving operating energy consumption.

Details

Industrial Lubrication and Tribology, vol. 70 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

To view the access options for this content please click here
Article
Publication date: 1 December 2001

A. Castañeda, L.M. Apátiga, R. Velázquez and V.M. Castaño

A spatial micropositioning device for the alignment of substrates employed in thin films synthesis by the so‐called combustion flame technique, utilized for producing thin…

Abstract

A spatial micropositioning device for the alignment of substrates employed in thin films synthesis by the so‐called combustion flame technique, utilized for producing thin diamond films, was designed and built. A combination of mechanical, electronic and optical components allowed, with high accuracy, the alignment of the substrate during the film deposition process. The system always kept the substrate surface perpendicular to the oxy‐acetylene flame produced by the torch, in such a way that each deposited film consists of a circular disk, approximately 4mm in diameter and 20μm thick, over the region of the substrate that intersects the inner acetylene‐rich flame. The films obtained under these conditions showed low nitrogen content, as confirmed by the Fourier‐transform infrared spectrum (FTIR), which is also presented. Accordingly, the present work represents the first step towards a complete automation of the combustion diamond deposition technique, aiming to design an operating industrial‐level technology.

Details

Assembly Automation, vol. 21 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

To view the access options for this content please click here
Article
Publication date: 7 August 2018

Kaleem Ahmad Najar, N.A. Sheikh, Mohammad Mursaleen Butt and M.A. Shah

The purpose of this study is to investigate the mechanical and tribological properties of the synthetic diamond coatings deposited on WC-Co cutting tools for their…

Abstract

Purpose

The purpose of this study is to investigate the mechanical and tribological properties of the synthetic diamond coatings deposited on WC-Co cutting tools for their prospective applications in mechanical industry. In this work, the concept of nanocrystalline diamond, microcrystalline diamond and multilayer-diamond coating systems were proposed and deposited on WC-Co substrates with the top-layer nanocrystallinity, optimum thickness and interfacial adhesion strength for load-bearing tribological and machining applications. Also, the overall mechanical and tribological properties of all synthetic diamond coatings were compared for the purpose of selecting a suitable type of protective layer used on the surfaces of WC-Co cutting tools or mechanical dies.

Design/methodology/approach

Smooth and adhesive single layered and multilayered synthetic deposited on chemically etched cemented tungsten carbide (WC-Co) substrates using predetermined process parameters in hot filament chemical vapor deposition (HFCVD) method. A comparison has been documented between diamond coatings having different nature and architecture for the purpose of studying their mechanical and tribological characteristics. The friction characteristics were studied experimentally using ball-on-disc type linear reciprocating micro-tribometer under the influence of varying load conditions and within dry sliding conditions. Nanoindentation tests were conducted on each diamond coating using Berkovich nanoindenter for the measurement of their hardness and elastic modulus values. Also, the wear characteristics of all sliding bodies were studied under varying load conditions using cumulative weight loss and density method.

Findings

Depositing any type of diamond coating on the cemented carbide tool insert increases its all mechanical and tribological characteristics. When using boron-doping onto the top-layer surface of diamond coatings decrease slightly their mechanical properties but increases the tribological characteristics. Present analysis reveals that friction coefficient of all diamond-coated WC-Co substrates decreases with the increase of normal load. Therefore, maintaining an appropriate level of normal load, sliding time, sliding distance, atmospheric conditions and type of diamond coating, the friction coefficient may be kept to some lower value to improve mechanical processes.

Originality/value

As the single layered synthetic diamond coatings have not given the full requirements of mechanical and tribological properties when deposited on cutting tools. Therefore, the multilayered diamond coatings were proposed and developed to enhance the interfacial integrity of the nanocrystalline and microcrystalline layers (by eliminating the sharp interface) as well as increasing the hardness of tungsten carbide substrate. However, when using boron doping onto the top-layer surface of diamond, coatings decreases slightly their mechanical characteristics but also decreases the value of friction coefficient.

Details

Industrial Lubrication and Tribology, vol. 70 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

To view the access options for this content please click here
Article
Publication date: 1 January 2004

Christianne V.D.R. Anderson and Kumar K. Tamma

We first provide an overview of some predominant theoretical methods currently used for predicting thermal conductivity of thin dielectric films: the equation of radiative…

Abstract

We first provide an overview of some predominant theoretical methods currently used for predicting thermal conductivity of thin dielectric films: the equation of radiative transfer, the temperature‐dependent thermal conductivity theories based on the Callaway model, and the molecular dynamics simulation. This overview also highlights temporal and spatial scale issues by looking at a unified theory that bridges physical issues presented in the Fourier and Cattaneo models. This newly developed unified theory is the so‐called C‐ and F‐processes constitutive model. This model introduces the notion of a new dimensionless heat conduction model number, which is the ratio of the thermal conductivity of the fast heat carrier F‐processes to the total thermal conductivity comprised of both the fast heat carriers F‐processes and the slow heat carriers C‐processes. Illustrative numerical examples for prediction of thermal conductivity in thin films are primarily presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 14 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 6 May 2020

Ramakant Rana, Qasim Murtaza and R.S. Walia

In this study, the tri-bological behaviour of the un-coated and diamond coated tungsten carbide was evaluated using the pin-on-disc test rig. The same was also tested on a…

Abstract

Purpose

In this study, the tri-bological behaviour of the un-coated and diamond coated tungsten carbide was evaluated using the pin-on-disc test rig. The same was also tested on a lathe machine tool. This paper aims to compare the tri-bological behaviour of coated tungsten carbide pin with un-coated tungsten carbide pin it also correlates the wear obtained from the two machines used.

Design/methodology/approach

Experiments were performed using L8 orthogonal array and results obtained on a pin-on-disc test rig under dry sliding process were optimized through a modern optimization technique i.e. genetic algorithm (GA). The response surface methodology model (L8 orthogonal array) formed the basis for the development of the GA model, which defines the conditions of minimum wear, minimum coefficient of friction and minimum surface roughness for the sliding process of the pin-on-disc test rig.

Findings

Implementation of the heuristic approach for optimization of input parameters for the combination of tool material used for the turning process. The initial approach involves tri-bological testing considering the same combination. The set of experiments further performed, inferred that the results were similar and that the diamond coating enhances the life of the tool.

Originality/value

Successfully synthesized the diamond coating on tungsten carbide tool material. Implantation of the heuristic approach, i.e. GA to tri-bological tests to identify the optimized level of input variables. Experimentation involves the tri-bological testing whose results were confirmed through performing experiments on the lathe machine tool.

Details

World Journal of Engineering, vol. 17 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

To view the access options for this content please click here
Article
Publication date: 20 June 2019

Xinbo Wang, Zhongwei Yin, Hulin Li, Gengyuan Gao and Jun Cao

The purpose of this paper is to study the frictional behaviors of CuAl10Fe3 journal bearings sliding against chromium electroplated 42CrMo shafts and diamond-like…

Abstract

Purpose

The purpose of this paper is to study the frictional behaviors of CuAl10Fe3 journal bearings sliding against chromium electroplated 42CrMo shafts and diamond-like carbon-coated 42CrMo shafts, respectively, under two different conditions and to compare the two kinds of friction pairs.

Design/methodology/approach

All journal bearing samples underwent 24 h running-in and repeatability verification. Then, the journal bearing friction experiments were carried out under two different conditions. After testing, the torques, friction coefficients, power consumptions and other parameters were obtained.

Findings

The pair of CuAl10Fe3 journal bearing and diamond-like carbon–coated shaft could drive greater load to start up than the pair of CuAl10Fe3 journal bearing and chromium electroplated 42CrMo shaft, but it had greater power consumption during the steady running period under the identical condition. With the changing of specific pressure or rotational speed, the friction coefficients had different variations. The frictional oscillations appeared at 32 rotations per minute under heavy loads for both kinds of pairs, the oscillation frequencies were equal to rotational frequency of the test shaft and the oscillation amplitude for diamond-like carbon coating was much greater.

Originality/value

These results have guiding significance for practical industrial applications.

Details

Industrial Lubrication and Tribology, vol. 71 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

To view the access options for this content please click here
Article
Publication date: 4 February 2014

Chen Wengang, Ge Shirong, Pang Lianyun and Zhang Yonghai

Three types of pattern on the monocrystalline silicon surface were prepared by using laser surface processing equipment. The DLC film and Si-DLC film on the patterning…

Abstract

Purpose

Three types of pattern on the monocrystalline silicon surface were prepared by using laser surface processing equipment. The DLC film and Si-DLC film on the patterning surface were deposited by using PECVD-2D plasma chemical vapor deposition sets. The paper aims to discuss these issues.

Design/methodology/approach

The tribological properties of the films were investigated by using the UMT-2 micro friction and wear tester. The surface topography, composition, hardness and elastic modular of the films were determined by Raman spectrum, nano mechanics tester and three-dimensional topography instrument. The worn surface topographies of the surface patterning films were tested by scanning electron microscopy.

Findings

The results show that the patterning monocrystalline silicon substrate surface has good anti-friction property under low load. The patterning DLC film and Si-DLC film surface have very good anti-friction property under all the test loads. The reason of these results is that the surface patterning film not only reduces the real contact area of the friction pairs but also has low surface bonding force.

Originality/value

This paper prepared three kinds of microscopic patterns on the monocrystalline silicon surface by using laser surface processing equipment. And then deposited DLC film and Si-DLC film on the patterning surface. All kinds of surface patterning monocrystalline silicon had very good anti-friction property under low load. And all kinds of surface patterning nano-hard film had perfect anti-friction property under all test loads.

Details

Industrial Lubrication and Tribology, vol. 66 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Abstract

Details

Circuit World, vol. 40 no. 1
Type: Research Article
ISSN: 0305-6120

Abstract

Details

Soldering & Surface Mount Technology, vol. 26 no. 1
Type: Research Article
ISSN: 0954-0911

To view the access options for this content please click here
Article
Publication date: 1 April 1994

Terry Ford

Organized by the Institute of Materials, this latest MMC conference was subtitled “Design and Innovation” and attracted delegates from research bodies, universities and…

Abstract

Organized by the Institute of Materials, this latest MMC conference was subtitled “Design and Innovation” and attracted delegates from research bodies, universities and industry. It enabled exchanges of information on these materials to be made and provided a view of the latest work being undertaken, as well as prospects for the future. The problems associated with the production of MMCs, as well as their potential, were explored, with a range of applications envisaged. As far as their possible use in aerospace is concerned, this is currently limited in scope, but developments and extensive testing will enable the necessary qualification criteria to be established and lead to a variety of uses.

Details

Aircraft Engineering and Aerospace Technology, vol. 66 no. 4
Type: Research Article
ISSN: 0002-2667

1 – 10 of over 1000