Search results
1 – 10 of 16Jun Cao and Zhongwei Yin
The purpose of this paper is to solve the problem of joint bearings that cannot work in high temperature because of their high frictional coefficients.
Abstract
Purpose
The purpose of this paper is to solve the problem of joint bearings that cannot work in high temperature because of their high frictional coefficients.
Design/methodology/approach
Two methods of inlaying graphites and liquid spraying of MoS2 are designed. The arrangement of graphites is shown and its frictional coefficients (COFs) are discussed. MoS2 coating is deposited by liquid spraying. The ingredients of liquid spraying of MoS2 are illustrated. Stresses, structure deformations and fatigue life are analyzed by finite element analysis.
Findings
Results show that both two designed methods can decrease COFs effectively. All stresses are in the limit of the maximum permissible stresses. The new designed bearings can be safety worked in sealed and high temperature environment which are proved by fatigue analyses.
Practical implications
Two new designs can help joint bearings work in nuclear plants because of their low COFs and litter wear. The new designs can improve bearings life.
Originality/value
Two methods of decreasing COFs of joint bearings are designed in this paper. The technologies are illustrated. The proper scopes of applications of two designed methods are discussed.
Details
Keywords
Jun Cao, Zhongwei Yin, Yuqing Cui, Hulin Li, Gengyuan Gao and Xinbo Wang
The purpose of this study was to solve the problem of most woven-fabric self-lubricating bearings that find it difficult to function at temperatures above 320°C, by designing a…
Abstract
Purpose
The purpose of this study was to solve the problem of most woven-fabric self-lubricating bearings that find it difficult to function at temperatures above 320°C, by designing a new type of new nuclear joint bearing. The results of this study will help designers to achieve accurate stress distribution, displacement deformation, fatigue life and damage of bearings. All of these can be a guide for designing self-lubricating joint bearings.
Design/methodology/approach
Finite element analysis is undertaken to simulate the new design bearings. To get the most appropriate and accurate results, the room temperature simulation (Simulation A), the modulus of elasticity that changes with temperature (Simulation B) and the thermal-structure-coupled simulation (Simulation C) are compared. The fatigue simulation is conducted to verify whether the self-lubricating method is reasonable and whether the bearing can function for over 60 years in an enclosed environment.
Findings
Stress distribution and displacement deformation of joint bearing can be accurately achieved via the thermal-structure coupled simulation. Work life and damage results have been achieved via the fatigue analysis, and the suggested working loads can be calculated via safety factors.
Originality/value
The newly designed joint bearing in which the graphite is laid on the outside of the inner ring functions and self-lubricates at temperatures above 320°C.
Details
Keywords
Cuicui Chen, Qian Yang, Qingan Chen, Yanhui Wang, Dong Xu, Hezong Li, Xiliang Zhang, Christopher M. Harvey and Jiwei Liu
This study aims to investigate the effects of graphite-MoS2 composite solid lubricant on the tribological properties of copper-based bearing materials under dry conditions.
Abstract
Purpose
This study aims to investigate the effects of graphite-MoS2 composite solid lubricant on the tribological properties of copper-based bearing materials under dry conditions.
Design/methodology/approach
The mixture of Graphite-MoS2 was inlaid in ZQSn6-6–3 tin bronze and ZQAl9-4 aluminum bronze matrix. These copper-embedded self-lubricating bearing materials were considered in friction pairs with 2Cr13 stainless steel, and their tribological properties were studied by using an MM200 wear test machine.
Findings
The results show that the friction coefficients and wear rates of copper-embedded self-lubricating bearing materials are lower than those of the ordinary copper-based bearing materials. The wear performance of the tin bronze inlaid self-lubricating bearing material is better than that of the aluminum bronze inlaid self-lubricating bearing material. The wear mechanism of the tin bronze bearing material is mainly adhesive wear, and that of the aluminum bronze bearing material is mainly grinding wear, oxidation wear and adhesive wear. The copper-embedded self-lubricating bearing materials had no obvious abrasion, whereas the aluminum bronze inlaid self-lubricating bearing material exhibited deep furrows and obvious abrasion under high loads.
Originality/value
These results are helpful for the application of copper-embedded self-lubricating bearing materials.
Details
Keywords
There must always be a danger that condition monitoring techniques aimed at the wear products of one particular couple may find interference, or even be blanketed by the products…
Abstract
There must always be a danger that condition monitoring techniques aimed at the wear products of one particular couple may find interference, or even be blanketed by the products of another couple. It is therefore essential for those in such work to recognize what new materials may have been introduced, but not infrequently component makers are unwilling to disclose at any early date the “secrets” of their new coatings. By reviewing the traditional materials, and both the developments and trends in purposely structured materials used in modern piston ring/liner technology it is hoped that some value will result to those engaged in the development of condition monitoring techniques.
Yubo Yang, Xiuhua Guo, Kexing Song, Fei Long, Xu Wang, Shaolin Li and Zhou Li
Copper matrix composites are widely used in high-voltage switches, electrified railways and other electric friction fields. The purpose of this study is to improve its wear…
Abstract
Purpose
Copper matrix composites are widely used in high-voltage switches, electrified railways and other electric friction fields. The purpose of this study is to improve its wear resistance and investigate the effect of hybrid carbon nanotubes (CNTs) and titanium diboride (TiB2) particles reinforced copper matrix composites on electrical wear performance.
Design/methodology/approach
CNTs and TiB2 particles were introduced into copper matrix simultaneously by powder metallurgy combined with electroless copper plating. Electrical wear performance of the composites was studied on self-made pin on disk electrical wear tester.
Findings
The results show that the friction coefficient and wear rate of (1CNTs–4TiB2)/Cu composite are respectively reduced by 40% and 25.3%, compared with single TiB2/Cu composites. The micron-sized TiB2 particles can hinder the plastic deformation of composites, and bear part of the load to weaken the wear rate of composites. CNTs with the self-lubricating property can form lubricating layer to reduce the friction coefficient of composites.
Originality/value
This work can provide a design method for further improving the wear properties of TiB2/Cu composites.
Details
Keywords
This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper…
Abstract
This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1977‐1998. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, ferrites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.
Details
Keywords
De‐Xing Peng, Cheng‐Hsien Chen, Yuan Kang, Yeon‐Pun Chang and Shi‐Yan Chang
The purpose of this paper is to investigate the tribological properties of liquid paraffin with SiO2 nanoparticles additive made by a sol‐gel method.
Abstract
Purpose
The purpose of this paper is to investigate the tribological properties of liquid paraffin with SiO2 nanoparticles additive made by a sol‐gel method.
Design/methodology/approach
The tribological properties of the SiO2 nanoparticles as an additive in liquid paraffin are measured using a ball‐on‐ring wear tester to determine the optimal additive concentration. The mechanism that wear and friction are reduced is studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and atomic force microscope (AFM).
Findings
Experimental results indicate that the sizes of the synthesized SiO2 nanoparticles are distributed uniformly and that the optimal concentrations of SiO2 nanoparticles in liquid paraffin is associated with better tribological properties than pure paraffin oil, and an anti‐wear (AW) ability that depends on the particle size.
Originality/value
It is shown in the paper that by reducing friction and AW, the lubricant prepared by the methods described can prolong operating hours of machinery.
Details
Keywords
Abdollah Afshar, Mohsen Shirazi, Masoud Rahman and Esmaeil Fakheri
The purpose of this paper is to evaluate the galvanic corrosion of nitinol orthodontic wires with six dental alloys in artificial saliva and consider the effect of initiated…
Abstract
Purpose
The purpose of this paper is to evaluate the galvanic corrosion of nitinol orthodontic wires with six dental alloys in artificial saliva and consider the effect of initiated localized corrosion and real surfaces of anode and cathode on galvanic current.
Design/methodology/approach
Linear polarization and cyclic polarization curves for each alloy in de‐aerated Duffo and Castillo's artificial saliva are obtained. Galvanic corrosion investigation is conducted by polarization curve intersection and mixed potential theory methods. In order to verify the initiation of localized corrosion, scanning electron microscopy is used.
Findings
Initiation of localized corrosion on the anode increases the galvanic current up to 45 times and therefore considering the effect of localized corrosion on galvanic corrosion is necessary. Placing stainless steel brackets or Aristaloy amalgam in direct contact to nitinol arch wire is not recommended.
Originality/value
In order not to underestimate the galvanic corrosion between two alloys, it is recommended to consider the effects of localized corrosion and anode/cathode surface area ratio. In this paper, an electrochemical method for estimating these factors is proposed.
Details
Keywords
Hui Su, Lanlan Liu, Yang Yang, Zhen Zhong, Song Xu, Yi Xie and Tangqing Wu
The purpose of this paper is to study the corrosion behavior of Q235 steel in the bentonite-based resistance-reducing agent (RRA) with different infiltration rates of underground…
Abstract
Purpose
The purpose of this paper is to study the corrosion behavior of Q235 steel in the bentonite-based resistance-reducing agent (RRA) with different infiltration rates of underground water.
Design/methodology/approach
The corrosion behavior of the steel in underground water was assessed by weight loss experiment, electrochemical impedance spectroscopy and polarization curve.
Findings
The results showed that the corrosion rate of the steel in the RRA pastes was much lower than that in the original acidic soil. The underground water infiltration slightly accelerated the corrosion rate of the steel in the RRA pastes, but the acceleration role is weak. The bentonite-based RRA can be compatibly applied in the acidic soil.
Originality/value
The bentonite-based RRA can significantly reduce the corrosion rate of the steel and is suitable to compatibly apply in the acidic soil.
Details
Keywords
Shu-Hao Deng, Xi Yang, Mao Wang and Jiao Wang
– The purpose of this paper is to improve anti-corrosion, self-cleaning, hydrophily and sterilization properties of aluminum (Al) alloy.
Abstract
Purpose
The purpose of this paper is to improve anti-corrosion, self-cleaning, hydrophily and sterilization properties of aluminum (Al) alloy.
Design/methodology/approach
A multifunctional coating for medical external application on Al alloy had been prepared by anodic oxidation, electrolytic coloring silver (Ag) and sealed in boiling water with nano-sized titanium dioxide (TiO2) particles. The multifunctional coating was characterized by X-ray diffraction, scanning electron microscope and energy dispersive spectroscopy. Other properties such as corrosion-resistance, wipe-resistance, hydrophilicity, photochemical decomposition and bactericidal antiseptic effect were also investigated.
Findings
The results demonstrate that a golden film with multi-function had been obtained for medical external application. The main phase of coating is amorphous Al2O3, and nano-sized silver particle is electrodeposited in bottom of film hole, while nano-sized TiO2 is sealed on the external surface of coating. The properties of film, such as anti-corrosion, self-cleaning, hydrophily, sterilization are better than those of Al alloy substrate.
Originality/value
Considering about this usage for medical external application, a multifunctional coating which has the properties such as decoration, anti-corrosion, sterilize and self-cleaning has been first prepared on Al alloy surface in the study. This coating would meet the requirements of medical external using and provide theoretical and practical foundation about Al alloy for medical use.
Details