Jiangsu Polytechnic University

Changzhou, China

Jiangsu Polytechnic University

Changzhou, China
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Xu B.,Nanjing University of Technology | Liu Y.,Nanjing University of Technology | Yin X.,Nanjing University of Technology | Yang W.,Nanjing University of Technology | Chen Y.,Jiangsu Polytechnic University
Corrosion Science | Year: 2013

The corrosion inhibition effect of 3-pyridinecarboxaldehyde thiosemicarbazone (3-PCT) on mild steel was studied in 1. M HCl solution by means of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The surface morphology of mild steel was examined with scanning electron microscopy (SEM) and the mechanism of inhibition was determined by the potential of zero charge (PZC) measurement at the metal-solution interface. Then molecular dynamics simulations were also executed for 3-PCT. The results show that 3-PCT is a good corrosion inhibitor, retarding both cathodic and anodic reactions in hydrochloric acid. The adsorption of 3-PCT on the mild steel surface obeys the Langmuir isotherm, and the thermodynamic parameters (Kads,Ea,δGads0) were also determined and discussed. © 2013 Elsevier Ltd.


Qiu J.H.,Jiangsu Polytechnic University
Solid State Communications | Year: 2010

Based on a phenomenological thermodynamical theory, the effect of the domain wall on the dielectric properties of the polydomain BaTiO3/SrTiO3 superlattices with 180° electric domains in the BaTiO3 layer is investigated. Theoretical analysis indicates that complete polarization suppression and the largest dielectric response take place at approximately 72% and 53% of the critical volume fraction of the SrTiO3 layer for the domain wall energy parameter A=3×107 and 5×107, respectively. The dielectric properties largely depend on both the volume fraction of the SrTiO3 layer and the domain wall energy parameter. Moreover, the gigantic dielectric response which occurs in single-domain BaTiO3/SrTiO3 superlattices cannot appear due to the 180° polydomain state in the BaTiO3 layer, which is in agreement with the previous prediction. The high domain wall energy parameter results in the stabilization of the paraelectric state in the BaTiO3 layer, however, the enhancement of the domain wall energy parameter within a certain scale increases the dielectric properties greatly. © 2010.


Zhang Y.,Jiangsu Polytechnic University
Journal of Computational and Theoretical Nanoscience | Year: 2010

Boundary lubrication effect is investigated in isothermal line contact elastohydrodynamic lubrication (EHL) by using the inlet zone analysis method and taking the nanometer-scale thin film lubrication analytical approach proposed by the author.1 Calculation of the load carried by the EHL contact is made for the film thickness in the Hertzian contact zone ranging from 2 nm to 20 nm when the dimensionless material parameter G is 4500, the dimensionless rolling speed U is 1.0E-12, and the compound curvature radius of the contact surfaces R is 10 mm. Calculation is also made for different contact-lubricant interaction strengths represented by the critical thickness parameter hcr of boundary film. Results show that when the film thickness in the Hertzian contact zone is on the 1 nm scale (or lower), the load carried by the EHL contact can be considerably increased when the boundary lubrication in the EHL contact is considered; Otherwise, the change of the carried load by the EHL contact because of boundary lubrication consideration is negligible, and conventional EHL model can cover the whole EHL contact. Results also show that the compressibility of the lubricant due to the contact-lubricant interaction considerably reduces the load-carrying capacity of the EHL contact when the Hertzian contact zone is in boundary lubrication. Copyright © 2010 American Scientific Publishers. All rights reserved.


Qian J.,Jiangsu Polytechnic University | Qian J.,Nanjing University of Technology | Shi H.,Nanjing University of Technology | Yun Z.,Nanjing University of Technology
Bioresource Technology | Year: 2010

In the present work the preparation of biodiesel from Jatropha curcas L. oil produced by two-phase solvent extraction (TSE) was studied. The experimental results of TSE process showed that the optimal extraction conditions were 30 g samples, 240 mL of extraction solvent mixture and methanol/n-hexane volume ratio 60:40, extraction temperature 35 °C, extraction time 30 min. Further, the effect of methanol recycling on the TSE process was also investigated. After TSE process, the investigations were carried out on transesterification of methanol with oil-n-hexane solution coming from TSE process in the presence of sodium hydroxide as the catalyst. The conversion could achieve 98% with 3:1 n-hexane/oil weight ratio, 60 °C reaction temperature, 7:1 methanol/oil mole ratio, 1.1% alkali catalyst concentration and 120 min reaction time. The properties of fatty acid methyl ester (FAME) product prepared from Jatropha curcas L. oil produced by two-phase solvent extraction met the ASTM specifications for biodiesel. Crown © 2010 Published by Elsevier Ltd. All rights reserved.


Wang M.,Jiangsu Polytechnic University
Computers and Mathematics with Applications | Year: 2010

In this paper, we obtain some new inequalities by means of the mean inequalities of random variables, which include generalizations of the Greub-Rheinboldt inequality. © 2010 Elsevier Ltd. All rights reserved.


Xu B.,Nanjing University of Technology | Yang W.,Nanjing University of Technology | Liu Y.,Nanjing University of Technology | Yin X.,Nanjing University of Technology | And 2 more authors.
Corrosion Science | Year: 2014

The inhibition effect of two Schiff's base derivatives on the corrosion of mild steel in 1.0. M HCl solution was studied by electrochemical techniques, SEM and theoretical calculation methods. The experimental results show that the inhibition efficiency of 2-pyridinecarboxaldehyde thiosemicarbazone (2-PCT) is higher than that of 4-pyridinecarboxaldehyde thiosemicarbazone (4-PCT), and both the two compounds are good inhibitors for mild steel in 1.0. M HCl. Potentiodynamic polarization curves show that the two inhibitors act as mixed type inhibitors. The adsorption of inhibitors obeys the Langmuir adsorption isotherm, and the thermodynamic parameters (Ea, Kads, δGads0) were calculated and discussed. The mechanism of inhibition was determined by PZC measurements and theoretical calculation methods. © 2013 Elsevier Ltd.


Zhang Y.,Jiangsu Polytechnic University
Journal of Computational and Theoretical Nanoscience | Year: 2011

A peformance analysis is presented for the hydrodynamic lubrication between two parallel plane surfaces which is generated by micro asperities. One surface is relatively hard and smooth, the other coupled surface is "soft" and rough with randomly distributed asperities obeying Gaussian distribution law in height. The two surfaces slide against one another and between them is filled with fluid. Micro lubrication is generated between the surface asperity and the smooth surface. This gives the load-carrying capacity and performance of the contact between the two surfaces. The micro lubrication is in a mode of mixed contact where in the namely Hertzian contact zone is boundary lubrication while in the inlet zone is mainly continuum fluid film lubrication. The effective contact-adhering layer method is used to analyze this mode of micro lubrication. In this method, the asperity surface is artifically completely adhered with a uniform rigid solid layer, between the adhering layer and the smooth plane is continuum fluid lubrication. The effective thickness of the contact-adhering layer is found from the load-carrying capacity analysis results of the same contact by considering the real non-continuum fluid film lubrication in the contact as developed before. When the asperity is elastic or fully plastic, the lubrication between the effective contact adheing layer and the smooth plane is elastohydrodynamic lubrication (EHL) or hydrodynamic lubrication in fully plastic asperity contact, both of which can be respectively analyzed by the previously developed theories. When the asperity is elastoplastic but mainly elastic, the continuum fluid lubrication between the effective adhering layer and the smooth plane is also analyzed by EHL theory. The present paper gives the analysis for the load-carrying capacity, contact stiffness, friction coefficient and maximum temperature rise of a single asperity contact and the statistical averaged load-carrying capacity, contact stiffness, lubrication film stiffness and maximum temperature rise of the whole contact between the two plane surfaces. In Part II will be given the detailed computational results for the contact performance for given operating conditions. These may yield insights into the contribution of boundary lubrication in an engineering mixed lubrication. Copyright © 2011 American Scientific Publishers.


Zhang Y.,Jiangsu Polytechnic University
Transactions of the Canadian Society for Mechanical Engineering | Year: 2010

The present paper proposes a new type of step bearing by specifically modifying the interfacial condition between the fluid film and the bearing surface and introducing the boundary slippage at those interfaces. Analysis for the load-carrying capacity and friction coefficient is presented for this kind of bearing. The comparison of the obtained analytical results with the conventional (no-slippage) step bearing results shows that modifying the interfacial condition and introducing the boundary slippage at the specific bearing surfaces can significantly increase the load-carrying capacity and reduce the friction coefficient of a step bearing. Design guideline, the load-carrying capacity and the friction coefficient are also presented for this bearing at optimum condition which reaches the maximum load-carrying capacity.


Zhang Y.,Jiangsu Polytechnic University
Journal of Computational and Theoretical Nanoscience | Year: 2011

The present paper is the subsequent research of the first part. It presents the results of the performance of the contact formed between two sliding parallel plane surfaces lubricated by micro asperities calculated from the analysis demonstrated in the first part, for an exemplary operating condition. It is shown that the load carried by the whole contact between the two surfaces is nearly linearly increased with the reductions of both the nominal distance between the two surfaces and the statistical average film thickness at the asperity contact center. It is found that the physical adsorbed layer boundary lubrication occurring in asperity contacts can not considerablely influence the load-carrying capacity, the contact stiffness and the stiffness of the lubrication film of the whole contact between the two surfaces, although it increases the load-carrying capacity of the whole contact. The reason is that the stiffness of the boundary lubrication film in an asperity contact is much larger than that of the asperity in compression. However, the boundary lubrication occurring in the contact significantly influences the local film thickness of the contact i.e., the lubrication film thickness in asperity contacts which is on the nanometer scale, the boundary lubrication which has more pronounced effects gives considerablely higher local film thicknesses of the contact. The boundary lubrication may be intimately relevant to the local lubrication film and contact failures. It is also found that the reduction of the asperity surface hardness increases the friction coefficient of an asperity contact when the asperity is in elastoplastic or fully plastic deformations; When the asperity is in fully plastic deformation, the friction coefficient of an asperity contact remains constant independent of the carried load by the asperity contact. The occurrence of the plastic deformation in an asperity helps to reduce the maximum temperature rise in an asperity contact, as compared to the calculation result based on the elastic asperity assumption. Copyright © 2011 American Scientific Publishers.


Zhang Y.,Jiangsu Polytechnic University
Flow, Turbulence and Combustion | Year: 2011

The present paper proposes a simplified model for calculating hydrodynamic lubrication film thickness in elastoplastic line contacts. According to the Saint-Venant's principle, the pressure in the contact is taken as uniformly distributed, this gives the contact surface elastic deformations in the inlet zone far away from the contact center close to real ones while gives those close to the contact center greater than real ones. This treatment is validated for hydrodynamic lubricated elastic contacts for relatively light loads and high rolling speeds. It gives the film thickness at the contact center a little higher than that calculated based on the real elastic model. The treatment is extended to a hydrodynamic lubricated elastoplastic line contact. The contact surfaces in the inlet zone are assumed as elastic and their deformations are calculated based on the uniform pressure distribution in the elastoplastic contact area. An inlet zone analysis is taken for obtaining the calculating equation of the hydrodynamic film thickness at the contact center. The equation overestimates the central film thickness but gives a satisfactory film thickness prediction for the heavy load which gives significant plastic deformations in the elastoplastic contact. It is found that when the load is lighter than 0.6 w pc, the contact can be taken as elastic when calculating the central film thickness, while when the load is heavier than 0.6 w pc, the contact can be taken as fully plastic; Here w pc is the critical load for the contact fully plastic deformation. The plastic deformation in an elastoplastic line contact is found to reduce the hydrodynamic lubrication film thickness in the contact. This reduction is greater for higher rolling speeds and heavier loads. However, it is significantly dropped with increasing surface hardness. © 2011 Springer Science+Business Media B.V.

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