Industrial Lubrication and Tribology

Study of a novel anti-wear additive used in ashless anti-wear hydraulic fluid : Table of Contents

Zhang Longhua — Sun Jul 26 14:15:03 BST 2009

Abstract:
Purpose – The purpose of this paper is to develop novel ashless additives and to meet the need for formulating ashless anti-wear (AW) hydraulic fluid or other industrial lubricating oils. This paper also aims to investigate the tribological behaviours and mechanism of an acrylate of dialkyl dithiophosphoric acid (ADDP), as an additive in some group I/II base oils compared with some traditional s-p containing AW additives. Design/methodology/approach – ADDP is synthesized in the laboratory. The chemical composition and structure of the lubricating additive are analyzed by means of infrared spectroscopy. Its extreme pressure (EP), AW and friction reduction properties as additive in base oils, compared with some traditional s-p containing AW additives, are investigated using a four-ball machine according to relative testing standards. The tribological mechanism is discussed according to the scanning electron microscope (SEM) analytical data. Findings – The results indicate that the four-ball PB value of the prepared ADDP in HVIWH650 is better than that of the IRGLUBE 353; the thermal stability of ADDP is equivalent to the zinc dialkyl dithiophosphate (ZDDP) and the SEM data show that the prepared ADDP additive could form a layer of uniform film on the worn surface serving as lubricant and protective film. This may be the chief reason why the prepared ADDP possesses better AW property than ZDDP. Research limitations/implications – However, more experimental studies such as the synergic effect with other additives should be performed, from which it could be learned whether the novel AW additive would be applicable in industrial oils. Practical implications – The results may be useful for the researchers to formulate some ashless industrial oils. Originality/value – A novel additive was synthesized in the laboratory; it would find a promising industrial application as an ashless AW additive.

Investigation of load carriage capacity of journal bearings by surface texturing : Table of Contents

Cem Sinanoglu — Sun Jul 26 14:15:03 BST 2009

Abstract:
Purpose – The purpose of this paper is to investigate and discuss the influence of the pattern, size and orientation of textures on journal bearing load carriage capacity. An important development in load carriage capacity of journal bearings can be obtained by forming regular surface structure in the form of threaded on their shaft surfaces. This is performed both theoretically and experimentally using shafts with textured (threaded) and untextured surfaces. Each screw thread can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication or as a micro reservoir for lubricant in cases of starved lubrication conditions. Design/methodology/approach – The pressure distribution and the load-carrying capacity are predicted using feed forward architecture of neurons. The inputs to the neurons are a collection of experimental data. These data are used to train the network using the delta-bar-delta, batch-backprop, backprop, and backprop-rand algorithms. The proposed neural model outperforms the available experimental system in predicting the pressure as well as load-carrying capacity. Findings – Theoretical models are developed using a neural network approach, and tests are performed, to investigate the potential of threaded textured surfaces in tribological components like mechanical seals, piston rings and journal bearings. In these tests, load carriage capacity is significantly increased with threaded textured shaft surfaces to the shafts with non-textured surfaces. Originality/value – The paper discusses a new modelling scheme known as artificial neural networks. A neural network predictor has been employed to analyze the effects of shaft surface profiles in hydrodynamic lubrication of journal bearing.

Frictional behavior investigation on three types of PTFE composites under oil-free sliding conditions : Table of Contents

Xue-Bin Yang, Xin-Qiao Jin, Zhi-Min Du, Tian-Sheng Cui, Shao-Kan Yang — Sun Jul 26 14:15:03 BST 2009

Abstract:
Purpose – The purpose of this paper is to investigate the frictional behavior of polytetrafluoroethylene (PTFE) composites under oil-free sliding conditions. Design/methodology/approach – The friction force and power consumption of pressure packing seals, which were, respectively, made of common filled PTFE, 30 wt% CF (carbon fiber) +?PTFE and C/C (carbon/carbon) +?PTFE, are studied in a reciprocating oil-free compressor arrangement. Their coefficient of friction is tested on a block-on-ring type tribometer. Findings – The results indicate that influence of mean sliding velocity on filled PTFE composites is apparently more predominant than the others. The friction force curvilinear path of 30 wt% CF+PTFE is hardly influenced by changing crankshaft turn angle. For C/C+PTFE, the effect of mean piston velocity on friction force is not evident. The results also indicate that the friction coefficient of C/C+PTFE is lower than that of 30 wt% CF+PTFE if their applied normal force exceeds 9.8?N. Furthermore, their variation curve of friction force is little different and the power consumption of C/C+PTFE is slightly higher than that of 30 wt% CF+PTFE. Research limitations/implications – Neither the effect of real contact area on friction coefficient measured in a tribometer nor the influence of the temperature on friction force and power tested in a compressor is not taken into consideration here. Practical implications – Owing to its good mechanical performances and frictional behaviors, C/C+PTFE is an optimum and promising material under conditions with sealing pressure up to 10?MPa and sliding velocity exceeding 4.0?m/s. Originality/value – A novel material called C/C+PTFE is considered to make packing rings for oil-free reciprocating compressors and its friction behaviour is tested on a refitted compressor.

The frictional behavior of composite materials under horizontal vibration : Table of Contents

Mohammad Asaduzzaman Chowdhury, Md. Maksud Helali — Sun Jul 26 14:15:03 BST 2009

Abstract:
Purpose – The purpose of this paper is to present the frictional behaviour of composite materials under external horizontal vibration. Variation of friction coefficient is investigated experimentally when mild steel pin slides on composite materials such as glass fiber reinforced plastic (GFRP) and cloth reinforced ebonite (commercially known as gear fiber). Design/methodology/approach – A pin-on-disc apparatus having the facility of vibrating the test samples in a horizontal direction is designed and fabricated. Horizontal vibration is created along (longitudinal direction), and perpendicular (transverse direction) to, the sliding direction. The experimental set-up has the facility to vary the amplitudes and frequencies of vibration while velocity of vibration is kept constant. Findings – The relative frictional behaviour of these materials and their dimensional analysis are yet to be investigated. Therefore an attempt is made to investigate the relative frictional property of the GFRP and cloth reinforced ebonite (commercially known as gear fiber) and the results of these composite materials are analyzed by dimensional analysis under horizontal vibration. Practical implications – It is expected that the applications of these results will contribute to the improvement of different concerned mechanical systems. Originality/value – It can also be noted that there are no clear correlations between friction- and other vibration-related operating parameters. Considering the above conclusion and lack of correlation, the paper meant to find out a suitable correlation and a way of observing the response of friction force by applying known frequency and amplitude of vibration in a particular direction. It is expected that the application of these results will contribute to the improvement of different concerned mechanical systems.

Investigation of antiwear additives for diester : Table of Contents

Hua Wu, Tian Ren — Sun Jul 26 14:15:03 BST 2009

Abstract:
Purpose – The purpose of this paper is to study tribological properties of two novel additives in the diester and provide adequate information on the relationship between the diester and the additives. Design/methodology/approach – The two 2-mercaptobenzothiazole derivatives, referred to as BZIA, BZOA, are synthesized with one pot; their tribological performances are evaluated using a four-ball friction and wear tester, and the worn surface was analysed with scanning electron microscope and X-ray photoelectron spectroscopy (XPS). Findings – The two compounds as the additives in the diester possess excellent load-carrying capacities, rather good anti-wear (AW) and friction reduction properties. According to the XPS results, both the additives reacted with counter-face metal and generated a sulphur-containing inorganic film and a complex adsorption film. The inorganic film obtained with the additive BZOA consisted of FeS2, FeSO4 and Fe2(SO4)3, whereas the inorganic film obtained with the additive BZIA consisted of FeS2 or FeS. The adsorption layer for the two additives contained N-containing compounds. Research limitations/implications – The interaction of the two additives with the diester needs to be further explored. Practical implications – Two useful, environmentally friendly, AW lubricating oil additives are synthesized with one pot. Originality/value – The paper provides a study of some N, S-containing heterocyclic compounds as environmentally friendly lubricating oil additives.

Characterization of biodegradation of straw-based biomass-oil in aqueous culture conditions : Table of Contents

Yanyan Fu, Xianguo Hu, Yufu Xu, Xifeng Zhu, Shaotong Jiang — Sun Jul 26 14:15:03 BST 2009

Abstract:
Purpose – When carrying out bioremediation of water polluted by biomass-oil, the stains which can degrade the biomass-oil efficiently should first be found. The purpose of this paper is to describe how adopted acclimation through the isolated strains degraded efficiently, and got reaction kinetics property. Design/methodology/approach – During the acclimation, the biodegradation process of biomass-oil is accorded approximately with the first-order reaction by the way of Sturm method which is described by measuring CO2 volume from the microbes' production. Findings – One kind of microbe, Aspergillus versicolor, separated from the activated sludge in the aeration tanks of paper-mill, is found to have the advantage of biodegradation in case of biomass-oil from rice straw by rapid thermal-liquidizing process. The biodegradation ability could be improved in aqueous culture under neutral and acidic conditions. The optimal temperature for biodegradation of biomass-oil is 40°C. The optimal inocula content for biodegradation of biomass-oil was 16 vol%. Research limitations/implications – The variation of lubricity of biomass-oil with biodegradation needs more attention. Practical implications – A basic research on the growth of a strain is shown, which is helpful for the biological treatment of biomass-oil pollution. Originality/value – One kind of fungi, Aspergillus versicolor, can be used for the biodegradation of biomass-oil. The effects of various conditions or parameters on biodegradation of biomass-oil are discovered in aqueous culture conditions in the case of Aspergillus versicolor.