Table of Content

25 February 2018, Volume 46 Issue 2

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Mechanical Engineering

Flow Analysis and Optimization for Non-Circular Gear Pump on the Basis of Numerical Simulation

 

ZENG Qingdun HUANG Jiaxing RONG Liangwan

2018, 46(2):  1-7.  doi:10.3969/j.issn.1000-565X.2018.02.001

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 In order to reveal the pulsation law of pressure and flow rate for a new kind of non-circular gear pump on the basis of oval gears used as working components， the true three-dimension unsteady numerical simulation of external non-circular gear pump is successfully implemented by the use of the dynamic mesh technique in the software Fluent． The pressure and flow fluctuations of oval gear pump are captured，and the flow field distribution， the law of pressure differences at mesh points and the law of outlet flow rate are obtained． Unexpectedly，the flow and pressure fluctuations of oval gear pump are larger than those of normal gear pumps although the flow increases as we wish，which can hardly meet the practical needs． In order to reduce the flow fluctuations， two identical pumps are used to compose a parallel gear pump in structure which makes the fluctuations of two pump outputs compensate

each other． Another simulation of the parallel gear pump proves that the flow fluctuation has a decrease of 56 percent，compared with the mono-bloc unit oval gear pump． Therefore， the new parallel gear pump is much more worthy in practical application． 

Design and Experimental Ｒesearch of Oil Bladder Type Pressure Simulation Control System

 

YANG Gang DU Linglong LIANG Laiyu CHEN Kai

2018, 46(2):  8-13,21.  doi:10.3969/j.issn.1000-565X.2018.02.002

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A pressure simulation control system of one deepsea pressure vessel is designed． Aiming at the large volume，high precision and realtime response pressure control requirements， the oil bladder type pressure simulation control mode is proposed． An oil-water isolation chamber with oil bladder is designed in the pressure simulation control system，and oil-water isolation and pressure transmission are realized through the oil bladder． High precision and realtime pressure control of water pressure in the large volume pressure vessel is realized by the electrohydraulic servo technology， the feasibility and advancement of the designed control system are validated by the pressure experiments． The system could be applied to the pressure performance， the sealing performance and the pressure simulation tests of the pressure hull of an underwater glider． 

Optimization Research For Variable Space Of Torque Converter Based On Main Effect Analysis Of Blade Angles

WANG Anlin YANG Zhixiong LI Wenjia

2018, 46(2):  14-21.  doi:10.3969/j.issn.1000-565X.2018.02.003

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 As torque converter ( TC) 's blade variable space is large and the fluidsolid coupling is strong， it takes plenty of time to optimize and it's difficult to realize TC's engineering design． Taking dual turbine torque converter ( TTC) as research object， the paper simplifies the variable space of TC based on main effect analysis of blade angles． On the basis of confirming the fluidsolid coupling simulation model's correctness with the data of bench test， the optimal Latin hypercube experiments are designed to realize the performance simulation of TTC with 8 blade angles． Using TC's comprehensive performance ( efficiency，torque ratio and starting torque) as evaluation indexes， the response surface function is built and optimized to get the influence levels of 8 blade angles on the comprehensive performance of TTC． Consequently， for example，using TTC's efficiency at low speed ratio as main evaluation index， it is found that pump's inlet angle，first turbine's outlet angle，stator's inlet angle and outlet angle significantly affect the performance of TTC while other blade angles do not． The research method that the paper proposes has a certain reference value for rapid and customized design of congeneric products． 

Prediction of Gear Wear Ｒate in Mixed Lubrication and Experimental Verification

 

ZHANG Jiange LIU Shaojun FANG Te

2018, 46(2):  22-30.  doi:10.3969/j.issn.1000-565X.2018.02.004

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 Gears with highspeed and heavyload always run in mixed lubricating conditions． Ｒough surfaces of gears experience heavy friction and high flash temperature，resulting in larger energy loss and accelerating surface wear failure． In order to predict tooth wear rate accurately under mixed lubricating conditions，a new wear analysis model is proposed so that it can accurately describe the process of wear in mixed lubricating area in a microscopic dimension． Before the implementation of wear analysis program， the effect is considered of a coupling thermo-elasto-hydrodynamic phenomenon in the contact area． Methods in the mathematical model of tooth wear have been pro

posed to decide parameters in the model and its application range is discussed． By studying the performance of spur gears in terms of contact situation，pressure distribution，rise of flash temperature，lubricating state，friction and wear trend， it is revealed that the tooth surface wear is affected by miscellaneous factors，and its distribution on the tooth surface is also nonlinear． The temperature rise will greatly change the lubrication and friction interface in the mixed lubricating state． At the same time，asperity contact effects bring about a larger local wear rate and violent fluctuation，and further exacerbate wear degree of the tooth surface． Finally，comparison between the prediction wear depth and the experimental measurements indicates close congruity． The verification of the gear wear test indi

cates that the prediction model can provide evidence for gear design and engineering application． 

Machining Method of Composite Cycloid Gear Based on the Kinematic Control of Shaping Cutter

 

LIU Chang SHI Wankai HAN Zhenhua XU Lang

2018, 46(2):  31-37.  doi:10.3969/j.issn.1000-565X.2018.02.005

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 In order to machine the novel composite cycloid gear，a machining method is developed on the basis of the kinematic control of involute shaping cutter． At first， the digital and discrete models of the effective tooth profile of composite cycloid gear and the tooth profile of involute shaping cutter are built． The relationship between composite cycloid gear and involute shaping cutter relative motion is analyzed in the machining process． The kinematic control model for machining composite cycloid gear is derived on the basis of conjugation theory of gear meshing． The movement parameters of CNC machine are solved，and these parameters are interpolated in a continuous conjugate motion． The continuous shaping of the effective tooth profile of composite cycloid gear is realized． Then， the central path of the spherical milling cutter for milling the root of composite cycloid gear is derived，and the selection method of milling cutter is presented． At last， the machining process of composite cycloid gear is simulated by the software Matlab． The simulation results demonstrate that the developed machining method not only is feasible but also has fairly high precision．

Adaptive Slicing Algorithm Based on Contour Line of CAD Model in 3D Printing

 

CHEN Songmao BAI Shigen

2018, 46(2):  38-43.  doi:10.3969/j.issn.1000-565X.2018.02.006

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 In the process of converting CAD ( Computer Aided Design) models into STL ( Standard Triangular Language) models in three-dimension ( 3D) printing，there exist such problems as reduction of surface accuracy and loss of structure information． In this paper，a adaptive layered method is proposed based on the contour line of CAD models，with an approach of angle grouping，by referring to a series of planes containing Z axis to cut CAD models with equal turning angle， rotating the intersecting contour lines of cutting planes and model surfaces to XOZ plane around the Z axis，and dividing the contour lines into differential segments，applying trigonometric function relations，probability and statistic method，and weighting to calculate the adaptive layered thickness of each layer for 3D printing STL files． The results of model printing show that the algorithm can reduce conversion error of STL files， improve printing accuracy and printing efficiency of 3D printings．

Precise Positioning Method of Electronic-Component Leads Based on Ｒotational Stereo Vision

 

KUANG Yongcong LI Jiayu LIANG Jinglun OUYANG Gaofei

2018, 46(2):  44-52,58.  doi:10.3969/j.issn.1000-565X.2018.02.007

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 At present most of the autoinserting machines adopt the vision positioning method with bottom-camera， but it is difficult for some leads in bottom images of components to be distinguished from the body． In order to improve the positioning reliability，a precise positioning method is proposed of electronic-component leads based on rotational stereo vision． In the proposed method，firstly，a rotational-axis calibration method with checkerboard is put forward，and system calibration is finished． Secondly，side images of the component leads are obtained from multiple angles，a sub-pixel feature point extracted method is proposed on the basis of spatial moment． Then，spatial positioning of leads is calculated by optimizing feature points of multiple images． A vision positioning system with backlight is built for experiment，experimental results show that with the number of images increasing， the accuracy of proposed method increases and converges; grabbing position and angle produce no effect on accuracy of proposed method; the proposed method possesses higher accuracy and is more stable than the traditional method． On the other hand，because images can be obtained when moving，the proposed method brings about higher efficiency than the traditional method． 

Ｒesearch on U-Shaped Assembly Line Balancing Problem on the Basis of Directed Network Theory

 

JIAO Yuling XU Liangcheng LI Jin ZHANG Peng LI Siben

2018, 46(2):  53-58.  doi:10.3969/j.issn.1000-565X.2018.02.008

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 For the optimization design and flexible production requirements of work stations for complex assembly lines in manufacturing enterprises，a solution based on the directed net theory is proposed． Firstly，combining with a simple example of assembly line balancing problem， it shows that the flow chart of assembly line satisfies the features of directed graph and is represented by directed graph matrix，which converts complex network graph information into computable data and realizes the assembly line of computer calculation and program design． Secondly，assembly line with 29 nodes is taken as an example; the mathematical model of assembly line balancing problem is established with the minimum time loss of assembly line as the optimization objective，under the constraint of the time，cycletime and precedence of job elements． At last， the balancing problem of assembly line and the design of U assembly line are calculated by the use of the network theory of directed graph and line balance rate reaches 93. 81%，which verifies the rationality and validity of the directed net theory to solve the assembly line balancing problem and realizes the calculation of computer program，which provides a new method for automation design of largescale assembly line equipment in manufacturing enterprises． 

A Study on Methods for Measuring Natural Frequency of Ｒubber Damped Dynamic Vibration Absorber

 

LI Liping LU Zhaijun QIN Wu QIU Yinyuan LIU Xiaoang SHANGGUAN Wenbin

2018, 46(2):  59-64,87.  doi:10.3969/j.issn.1000-565X.2018.02.009

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 Because the dynamic stiffness of a rubber component depends on the excitation amplitude and the excitation frequency，the influence of excitation methods and excitation values on the natural frequency of a rubber damped DVA is studied in this paper． In general，the natural frequency of the DVA is only considered frequencydependent，ignoring the amplitude correlation． The natural frequency of a rubber damped DVA is measured and compared under excitations of constant amplitude，constant acceleration，random acceleration，pulse excitation from a shaker and force hammer percussion，respectively． It is concluded that the measured natural frequency using force hammer excitation method does not well characterize the natural frequency of the dynamic vibration absorber in generic applications． The test method of the natural frequency of the dynamic vibration absorber described in this paper can provide the basis for the measuring natural frequency of a rubber damped DVA under the actual vibration condition． 

Longitudinal Dynamic Analysis and Parameter Optimization of Electric Vehicle Driven by In-wheel Motor

 

ZUO Shuguang LI Duoqiang MAO Yu WU Xudong

2018, 46(2):  65-72.  doi:10.3969/j.issn.1000-565X.2018.02.010

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 The in-wheel motor produces torque ripple，which exerts the wheel boss directly． It causes the longitudinal dynamic problems，such as fluctuation of tire slip rate and longitudinal force． Accordingly， the model characteristic of electric wheel is firstly analyzed and three indexes are proposed to evaluate the longitudinal performance of electric wheel． Secondly， the sensitivity of system parameter is analyzed，and the law is detected of longitudinal acceleration which is mainly affected by the mass of vehicle body and in-wheel motor． The error of slip ratio and fluctuation of load torque depend on mass parameters，circumferential rigidity of tire and tread rigidity． Finally， the parameter optimization determines the improvement of the parameter value of the three indexes and it is found that parameter optimization is able to cause each index to be radically reduced in maximum value under the condition of corresponding models． 

Optimization of Vibration Ｒeduction of Mistuned Blades Based on Prestressed Component Mode Synthesis Method

ZHANG Hongyuan YUAN Huiqun YANG Wenjun ZHAO Tianyu

2018, 46(2):  73-80.  doi:10.3969/j.issn.1000-565X.2018.02.011

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 In order to reduce the level of the vibration localization of a mistuned bladed disk system by means of the pre-stressed component mode synthesis method，a reduced finite element model of the bladed disk system of an aeroengine compressor is constructed． Then，the natural frequencies with different mode truncation numbers are calculated，and through comparative analysis，the minimum mode truncation number satisfying the calculation precision is obtained． Moreover，the degree of freedom of the global model is reduced． Based on the reduced model，a blade vibration arrangement optimization algorithm is put forward，and at each iteration of the algorithm，only the substructure of a switching blade position is generated，while other blades data files remain unchanged． The results show that the constructed optimization algorithm takes into account both the model accuracy and the calculation speed，and it can greatly reduce the blade vibration amplitude and thus significantly reduce the vibration localization of the bladed disk system． 

Influence of Two-phase Flow Physical Properties on Emulsification Using Novel Parallelized Multi-Scale Channels

 

LI Jing LIAO Pan HONG Hui

2018, 46(2):  81-87.  doi:10.3969/j.issn.1000-565X.2018.02.015

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The hydraulic servo system generally regards the oil pressure as a constant，but the large flow condition and the pipeline effect in the long pipe will cause the oil supply pressure to fluctuate． These supply pressure chan-ges the result in servo system dynamic characteristic variation and thus degrade the control performance． To solve this problem，the changing oil supply pressure is estimated as an unknown parameter of the servo system based on the BackStepping control method． When Lyapunov functional derivative containing the estimation term isused，the principle must be negative and estimation method of the oil supply pressure is thus obtained． The servo system can adapt to the uncertain changes in supply pressure and keep precise position tracking performance． Experimental results show that the proposed estimation controller has higher position tracking accuracy when compared with the controller with good knowledge of supply pressure value．


Chemistry & Chemical Engineering

A Study of Microfibrous Entrapped Cu/Cr/Ag Impregnated Carbons for CO Oxidation

 

LUO Chao FAN Shuanshi YAN Ying ZHANG Huiping

2018, 46(2):  88-92,101.  doi:10.3969/j.issn.1000-565X.2018.02.013

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The microfibrous entrapped Cu/Cr/Ag impregnated carbon composites ( MFC) were prepared by wet layup papermaking and sintering process with micronsized stainless steel fibers and commercial granular Cu/Cr/Ag impregnated carbons ( GIC) as main raw materials． SEM images showed that the impregnated carbons were entrapped into a well sinterlocked three-dimensional network of stainless steel fibers． Nitrogen adsorption test showed that the pore structure and specific surface area of the impregnated carbons in composites were almost the same as commercial impregnated carbons． The result of XＲD，XPS and TPＲ all indicated that the active components of impregnated carbon were reduced． Catalytic performances for CO were investigated in structured fixed bed reactor filled with GIC and MFC with the height ratio of 1∶ 1，the experimental results showed that the conversion of CO over MFC decreased，which matched with the results of XＲD，XPS and TPＲ． 

Plasticizer Prepared by Catalytic Epoxidation of Soybean Oil Based on Deep Eutectic Ionic Liquid

 

CHANG Jie WANG Ju LIU Yong ZHOU Zhining FU Yan

2018, 46(2):  93-101.  doi:10.3969/j.issn.1000-565X.2018.02.014

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 In order to improve the efficiency of epoxidation，the environmentfriendly plasticizer was synthetized by catalytic epoxidation of soybean oil in solventfree system when deep eutectic ionic liquid was used as the acidic phase transfer catalyst，with choline chloride ( ChCl) being a hydrogen bond acceptor and oxalic acid dihydrate in molar ratio of 1∶ 1 and peroxyformic acid being oxygen supplying agent． The effects of reaction temperature，reaction time，catalyst，hydrogen peroxide，and formic acid dosage on epoxide yield of raw oil by the single factor experiment were investigated． The product prepared under the optimal conditions had light color with the high epoxide yield of 90. 32% and epoxy value of 6. 85%． The quality of product conformed to Chinese national standard， and the catalyst was easily separated and recycled． The characterization results from Fourier transform infrared spectroscopy ( FTIＲ) and nuclear magnetic resonance spectroscopy ( 1H NMＲ) showed that the conversion of unsaturated double bonds in raw material oil was basically complete with the high epoxide yield and excellent selectivity; thermal analysis ( TG-DSC) proved the prepared epoxidized plasticizer along with the initial decomposition temperature of 265℃ formed the trend to lose its weight until temperature was just above 223℃，respectively，displaying the better thermal stability

Influence of Two-phase Flow Physical Properties on Emulsification Using Novel Parallelized Multi-Scale Channels

 

ZHOU Peipei HU Xiaofang LI Qiong PENG Xiangfang

2018, 46(2):  102-108,117.  doi:10.3969/j.issn.1000-565X.2018.02.015

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In this paper，we study the development of novel multiscale parallel micro-channel contactor for monodisperse waterin-oil emulsification． Oils with different physical properties ( pure oil，0. 3% span83，0. 4% span83) and water are chosen as a continuous phase and a dispersed phase respectively． By using novel multiscale contactor ( sixteen parallel Ytype channels) which offers an equal distribution of flow rate with low energy cost ( less than 35J/kg) ，we have studied and discussed the influence of two-phase flow physical properties ( such as flowrate ratio，surface intension and capillary number) on the emulsion polydispersity experimentally and numerically． Capillary number ( Ca) plays an important role in emulsification progress，and when Ca is less than 0. 01， the mono-disperse emulsion is better． As the surface tension of the two-phase flow increases， the emulsion poly-dispersity is lower and the density of the emulsion reduces． When the surface tension rises to 27. 6mN/m， the polydispersity ( Pw) ranging from 3. 0% to 5. 8% is half of the Pw of water -0. 3% span83 emulsions．

Flow Boiling Pressure Drop Characteristics of Ｒ141b in Extreme Wettability Micro-Channels

 

LUO Xiaoping LIAO Zhengbiao ZHOU Jianyang WANG Wen ZHANG Lin

2018, 46(2):  109-117.  doi:10.3969/j.issn.1000-565X.2018.02.016

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By using the refrigerant Ｒ141b as the experimental working fluid，a flow boiling experiment was conducted in the ordinary hydrophilic，super-hydrophilic and super-hydrophobic rectangular micro-channels with crosssectional size of 1mm ×2mm and wall contact angles of 67°，0° and 156° respectively， the pressure of three kinds of surface micro-channel along the measuring point was also compared so as to analyze the pressure drop characteristics of Ｒ141b flow boiling in micro-channels with extreme wettability ( super-hydrophilic and super-hydrophobic) ． The results showed that the ratio of pressure drop components in the extreme wetting micro-channel is approximately the same as that of an ordinary hydrophilic micro-channel，and the friction pressure drop of unit length all increase with the rise of mass flux，inlet temperature and heat flux density; The total pressure drop of microchannels with the super-hydrophobic surface is the maximum，which is 1. 08 ～1. 17 times of the super-hydrophilic surface，and the slope of the pressure curve in the single-phase flow area is the smallest and the slope of the pressure curve in the two-phase flow area is the largest; The Qu-Mudawar model was revised by introducing the surface energy parameter s， the new correlation can better predict the experimental value and the average absolute error is 10. 7%． 

The Combustion Characteristic and Kinetic of Fuels Constituted with Sludge and Waste Cooking Oil

 

LOU Bo XUE Yanzhen

2018, 46(2):  118-123,139.  doi:10.3969/j.issn.1000-565X.2018.02.017

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 The new fuels are fabricated by mixing municipal sludge ( MS) with waste cooking oil ( WCO) ，providing a new method for waste resource utilization． The combustion characteristic of fuels with different blending ratios ( the mass ratios between sludge and waste cooking oil are 1∶ 0. 0，1∶ 0. 1，1∶ 0. 2，1∶ 0. 3，1∶ 0. 4，0∶ 1. 0，respectively) are investigated by means of thermogravimetric simultaneous thermal analyzer in the paper，and the result shows that the combustion characteristic indexes increases with the rise of waste cooking oil proportion，while the burnout temperature behaves oppositely，which suggests that the addition of WCO is beneficial for the combustion and burnout of MS． The reaction kinetics is analyzed by Ozawa-Flynn-Wall and Friedmen methods ( two modelfree methods) at the heating rate of 10，20，30℃ /min，finding after calculating the average activation energy that: When the mixing mass ratio is 1∶ 0. 3，the average activation energy of the blended fuel reaches the minimum with the values of 149. 2kJ/mol ( OFW) and 139. 5kJ/mol ( Friedmen) ，respectively，and here the blended fuels at the mass ratio possess a lower burnout temperature ( 575. 5℃) ． 

Quantitative Analysis of Ｒisk Ｒeduction of Natural Gas Transmission Pipeline with Explosion Proof Wall

 

CHEN Peizhu CHEN Guohua QI Shuai ZHOU Zhihang

2018, 46(2):  124-130.  doi:10.3969/j.issn.1000-565X.2018.02.018

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The control function of safety-prevention measures and the effect of mitigating safety measures on reduction of accident consequences are seldom considered in the analysis assessment of a general long-distance natural gas pipeline risk． A method that can quantify the effect of the explosion proof wall in quantitative risk analysis of a long-distance natural gas pipeline is proposed． Firstly，the attenuation rate calculation formula of the explosion proof wall resisting explosion shock wave overpressure of a long-distance natural gas pipeline is defined，and then the method to solve the attenuation of shock wave overpressure in a sensitive target area after the explosion proof wall is used． Finally，through correcting the accident parameter value based on the energy equivalent principle， an analysis is performed of the risk reduction level of a sensitive target area surrounding pipeline after the explosion proof wall was constructed． The case study suggests that the average rate of reduction of shock wave overpressure in sensitive target area after the explosion proof wall about 50. 05% was constructed; the individual and the social risk is reduced to an acceptable level． The quantitative characterization method of safety measures in quantitative risk assessment can provide technical reference for the construction of safety facilities in the surrounding area of a longdistance natural gas pipeline． 

Materials Science & Technology

Study on Thermal-Ｒesponse Characteristic of Polymer Materials to Synergism of High-Frequency Electric Field and Normal Stress Field

 

YANG Zhitao TONG Yizhang XU Wenhua YIN Xiaochun ZHANG Guizhen QU Jinping

2018, 46(2):  131-139.  doi:10.3969/j.issn.1000-565X.2018.02.019

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 Currently，polymer materials are processed by high temperature plasticizing and low temperature molding． These processing needs to spend a lot of energy and causes the degradation of polymers and additives， reducing product performances and recovery． Therefore，this article introduces highfrequency electric field into hotpressing process of polymers，making the materials plasticize in synergism of normal stress field and highfrequency electric field at low temperature． The dependence of pressure and temperature on thermalresponse of polymer materials to the high frequency electric field，as well as the mechanical properties of pure polymer plates which are prepared at critical plasticizing temperature point， is studied in depth; a model of temperaturerising is also reasonably established． The results show that the stronger polarity of polymer materials， the higher dielectric loss and absorbed heat will be; the absorbed heat of polar materials and amorphous polymer are positively related to the processing pressure，while the absorbed heat of non-polar crystalline materials have the best pressure point in which materials absorb the maximal heat． Homo-polymer have the best temperature points for heat absorption，while the absorbed heat of copolymer exponentially increase with the processing temperature rising． The tensile properties of specimens with highfrequency electric field improved significantly when compared to the specimens without highfrequency electric field，proving the existence of plasticizing behavior at low temperature under the synergism of normal stress field and  highfrequency electric field

Effect of Phosphate on the Mechanics and Degradation Properties of Dolomite Porcelain

 

ZHANG Zhijie LI Yuqin ZHANG Chenyang ZHONG Mingfeng

2018, 46(2):  140-146.  doi:10.3969/j.issn.1000-565X.2018.02.020

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To improve the mechanical properties and degradation performance of dolomite porcelain，we change the microstructure of dolomite porcelain by the introduction of phosphorus． Xray diffraction ( XＲD) accompanied with Ｒietveld refinement，Ｒaman spectroscopy， infrared spectroscopy ( FTIＲ) ， 31P magic angle spinning-nuclear magnetic resonance spectroscopy ( MAS-NMＲ) and scanning electron microscopy ( SEM) are used to characterize the structure and properties of Pfree and P-containing samples． It is found that the content of glass phase increase obviously in the P-containing formula，and the glass phase has formed a new structure，namely，Si( Al) —O—P— O—Ca( Mg) ，which makes the ceramic connected more closely and the mechanics properties increase from 24. 99MPa to 38. 73MPa． Under acidic conditions， the P—O bonds in the glass phase is easily hydrolyzed，and the P—O—Mg is more preferentially destroyed than P—O—Ca，which accelerates the disintegration of the glass phase and greatly improves the degradation of the dolomite porcelain．