建陶行业低增长形势下陶瓷机械的发展趋势

本文主要阐述了近几年陶机的市场形势、市场特点、行业特征,部分陶机的发展现状,以及陶机的发展趋势。指出了在整个建陶行业缓慢增长模式下,陶机企业的生存之道。

Micro-displacement amplifying mechanism driven by piezoelectric actuator

Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding should be long-travel, high-frequency and high-precision in non-circular precision turning, a new one-freedom flexure hinge structure is put forward to amplify the output displacement of piezoelectric actuator. Theoretical analysis is done on the static and dynamic characteristics of the structure, differential equations are presented, and it is also verified by the finite element method. It's proved by experiments that the output displacement of the structure is 293 μm and its resonant frequency is 312 Hz.

Structure and mechanical properties of ZrO_2-mullite nano-ceramics in SiO_2-Al_2O_3-ZrO_2 system

ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray diffraction, infrared spectrum, scanning electron microscope and differential scanning calorimetric. And the mechanical properties of the nano-ceramics were studied. The results show that the bulks are still in amorphous state at 900 ℃ and the t-ZrO2 forms at about 950 ℃ with a faint spinel-like phase which changes into mullite on further heating. ZrO2 and mullite become major phases at 1 100 ℃ and an amount of m-ZrO2 occur at the same time. The sample heated at 950 ℃ for 2 h and then at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with ball-like grains in size of 20-50 nm. With the increase of crystallization temperature up to 1 350 ℃, the grains grow quickly and some grow into lath-shaped grains with major diameter of 5 μm. After two-step treatment the highest micro-hardness, flexural strength and fracture toughness of the samples are 13.72 GPa, 520 MPa and 5.13 MPa·m1/2, respectively.

The Fouling Mechanism of Ceramic Membranes Used for Recovering TS-1 Catalysts

Ceramic ultrafiltration membranes were used to separate titanium silicalite-1 （TS-1） catalysts from the slurry of catalytic ammoximation of cyclohexanone to oxime. Silica was shown to have a great effect on membrane fouling in the alkaline environment of this system. In the ammoximation system, there are three main silica sources, which are residual silica on the catalyst particles surface during preparation, silica dissolved from TS-1 catalyst particles by ammonia solvent, and silica sol added into the reaction slurry to inhibit the dissolution erosion of the TS-1 catalyst. The silica dissolved by ammonia has been proved to influence membrane fouling most among the three silica sources. This was because the amount of silica dissolved by ammonia was the largest, and the polymerization of silica monomers at high concentration caused colloid particles formation, which led to a dense cake layer depositing on the membrane surface. Meanwhile, the size reduction of catalyst particles caused by alkaline dissolution also increased specific resistances of cake layers.

Disease-specific health-related quality of life and its determinants in liver cirrhosis patients in Lithuania

AIM: To evaluate disease-specific quality of life (QOL) in liver cirrhosis patients and to compare it with those of a healthy population. Also an important objective was to assess whether QOL in liver cirrhosis patients differs by age and gender, by type and severity of disease. METHODS: The case group of 131 liver cirrhosis patients was selected. The control group of 262 was enrolled from a healthy population according to the scheme of case-control study. Clinical, demographic, laboratory data were collected. QOL was measured with a specific chronic liver disease questionnaire (CLDQ), which was translated and validated in Lithuanian. QOL scores were compared between groups by age, gender, type and severity of disease. Cronbach’s alpha statistics calculation was used for evaluation of internal consistency reliability. Student’s t test or ANOVA were used for evaluation hypothesis about probability equation. RESULTS: QOL was significantly lower in liver cirrhosis patients than in healthy population (59.5 ± 18.3 vs 85.3 ± 12.3, P < 0.001). The significant QOL differences between case and control groups were observed in domains of worry and abdominal symptoms, the smaller differences-in emotional functions and systematic symptom domains. Significantly worse QOL was in observed patients with increased clinical severity of the disease measured by Child-Pugh class. Age, gender and etiology of disease had an insignificant effect on QOL in cirrhotic patients. CONCLUSION: QOL was significantly impaired in all CLDQ domains in liver cirrhosis patients. Increase in severity of disease was the major factor associated with poorer QOL.

Properties and mechanism of red mud in preparation of ultra-lightweight sludge-red mud ceramics

New ultra-lightweight sludge-red mud ceramics(ULS-RMC) were prepared by red mud(RM),clay and dried sewage sludge(DSS).The properties and mechanism of RM in the preparation of ULS-RMC were discussed.The chemical components,thermal properties and mineral phases of RM were determined by energy dispersive X-ray(EDX),differential scanning calorimetry/thermal gravimetric analysis(DSC/TGA) and X-ray diffraction(XRD),respectively.Constant dosage of DSS to clay and different amounts of RM were utilized in the preparation of ULS-RMC.Physical properties test(bulk density,grain density,water absorption and expansion ratio),XRD and scanning electron microscopy(SEM) were employed to characterize the ULS-RMC.The results show that RM exhibits high hydroscopic property and good water-retention property,and bloating property and fluxing property of RM are caused by abound of gaseous components and flux,respectively.The two chemical properties are utilized to discuss the mineral phases and microstructures differences between ULSC and ULS-RMC.

Microstructures and properties of PVD TiAlN coating deposited on cermets with different Ti(C,N)grain size

In the present work,TiAlN coatings were deposited on Ti(C,N)-based cermet substrates by physical vapor deposition method.Emphasis was focused on the influence of grain size of cermet substrates on the microstructure,growth behavior,mechanical properties,adhesion strength and wear behavior of the coatings.The results show that finer Ti(C,N)grain size leads to higher nucleation density and lower growth rate of coatings,indicating the crystallite size of the TiAlN coatings decreases with decreasing Ti(C,N)grain size.Nanoindentation tests show that the coatings deposited on cermets of the finest grain size exhibit the highest hardness(H),elastic modulus(E),H/E and H3/E2 of 34.5 GPa,433.2 GPa,0.080 and 0.22,respectively.The adhesion strength between coating and substrate is also enhanced with decreasing Ti(C,N)grain size by scratch test,which corresponds to the grain size and H/E and H3/E2 of the coating.Besides,the lower surface roughness and better mechanical properties of the coating deposited on finer grained cermet contribute to the better wear resistance of the coating.

Densification mechanism of stereolithographical dense Si_(3)N_(4) ceramics with CeO_(2) as sintering additive by field assisted sintering

Combining sintering additive with field assisted sintering,stereolithographical dense Si3N4 ceramics was successfully fabricated.Owing to a large amount of polymer during the stereolithography,the green parts have the characteristics of low powder loading and high porosity.Adjusting the process parameters such as sintering temperature and soaking time can effectively improve the density of the specimens.The stress exponent n of all specimens is in a range of 1 and 2,which is derived from a modified sintering kinetics model.The apparent activation energy Qd of stereolithographic Si_(3)N_(4) ceramics sintered with applied pressures of 30 MPa,40 MPa,and 50 MPa is 384.75,276.61 and 193.95 kJ/mol,respectively,suggesting that the densification dynamic process is strengthened by raising applied pressure.The grain boundary slipping plays a dominating role in the densification of stereolithographic Si3N4 ceramics.The Vickers hardness and fracture toughness of stereolithographic Si3N4 ceramics are HV10/10(1347.9±2.4)and(6.57±0.07)MPaAbstract:Combining sintering additive with field assisted sintering,stereolithographical dense Si3N4 ceramics was successfully fabricated.Owing to a large amount of polymer during the stereolithography,the green parts have the characteristics of low powder loading and high porosity.Adjusting the process parameters such as sintering temperature and soaking time can effectively improve the density of the specimens.The stress exponent n of all specimens is in a range of 1 and 2,which is derived from a modified sintering kinetics model.The apparent activation energy Qd of stereolithographic Si3N4 ceramics sintered with applied pressures of 30 MPa,40 MPa,and 50 MPa is 384.75,276.61 and 193.95 kJ/mol,respectively,suggesting that the densification dynamic process is strengthened by raising applied pressure.The grain boundary slipping plays a dominating role in the densification of stereolithographic Si3N4 ceramics.The Vickers hardness and fracture toughness of stereolithographic Si3N4 ceramics are HV10/10(1347.9±2.4)and(6.57±0.07)MPa·m^(1/2),respectively.

Effect of nucleating agents on microstructure and mechanical properties of SiO_2-Al_2O_3-ZrO_2 glass-ceramics

SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength （120MPa） than others.

Bonding mechanism of X10CrNi18-8 with Ni/Al_2O_3 composite ceramic by pressureless infiltration

Abstract： An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNil8-8 steel melt on 30% （mass fraction） Ni-containing alumina based composite ceramic （Ni/Al2O3） at 1 600 ℃. The infiltration quality and interfacial bonding behavior were investigated by SEM, EDS, XRD and tensile tests. The results show that there is an obvious interfacial reaction layer between the alloying steel and the Ni/Al2O3 composite ceramic. The interfacial reactive products are （FexAly）3O4 intermetallic phase and （AlxCry）2O3 solid solution. The interracial bonding strength is as high as about 67.5 MPa. The bonding mechanism of X10CrNi 18-8 steel with the composite ceramic is that Ni inside the ceramic bodies dissolves into the alloy melt and transforms into liquid channels, consequently inducing the steel melt infiltrating and filling in the pores and the liquid channels. Moreover, the metallurgical bonding and interfacial reactive bonding also play a key role on the stability of the bonding interface.

Thermal decomposition and mechanical properties of hydroxyapatite ceramic

Pure hydroxyapatite（HAP）ceramic and HAP composite ceramic with B2O3 were prepared by isostatic press forming and pressureless sintering.The relationships between thermal decomposition ratio and mechanical properties for pure HAP ceramic and the composite ceramic were investigated by means of FTIR,X-ray diffraction and three-point bending method.The results indicate that the decomposition ratio of pure HAP ceramic increases with ascending the sintering temperature and nearly reaches 80%at 1 350？殆or the HAP composite ceramic,the thermal decomposition is inhibited obviously due to the addition of B2O3.The added B atoms incorporate into the crystal lattice of HAP to form solid solution,resulting in an enlargement in the crystal spacing and an improvement in the binding strength of HAP crystal cell.Thermal decomposition ratio of HAP decreases but bending strength and fracture toughness are enhanced for HAP composite ceramics.However,when the added B2O3 is more than 5%（mass fraction）,HAP decomposition is promoted and a steady？-TCP is formed due to the fact that when B atoms with higher negative electricity are combined with O,sp2 and a full-air p are formed,and those voids have a strong trend to intake of the outer electrons.So,it is very possible to occupy the place where HAP loses OH - or PO4 3- .

In situ synthesis and characterization of Ca–Mg–Al hydrotalcite on ceramic membrane for biodiesel production

In situ surface synthesis of Ca–Mg–Al hydrotalcite(HT) on inorganic ceramic membrane(CM) was investigated with urea as precipitator. The effects of molar ratio of raw materials, crystallization time, and temperature on surface synthesis of HT were examined. The as-prepared HT/CM samples were characterized by XRD and SEM and an in situ growth mechanism of HT on CM was proposed. KF/HT/CM obtained by loading potassium fluoride(KF) on the HT layer by impregnation and calcination method was used as catalyst for transesterification between palm oil and methanol. The comparison of KF/HT/CM and pure KF/HT powder under identical reaction conditions shows that the production of fatty acid methyl ester is equivalent, which means that the use of inorganic catalytic membrane in the transesterification is a viable alternative.

Effect of sintering atmosphere on microstructure and properties of TiC based cermets

The effect of the sintering atmospheres (vacuum, N_2, Ar) on the microstructures and properties of the TiC based cermets was studied using XRD, SEM/BSE and energy dispersive spectrometer. Compared with the alloy sintered in vacuum, the carbon content of the specimen sintered in N_2 and Ar is lower by 0.5%; and the nitrogen content is higher by 0.3% when sintered in nitrogen. The central part of the ring structure may be carbide with either a high W or Ti content. The ring structures are (Ti, W, Ta, Mo, Co, Ni)C solid solutions with different metallic elements and distributions. The composition of the binder phase is (Co, Ni) solid solution with different Ti, W, Ta, Mo, C contents. The structures are uniform for the cermets sintered in vacuum and the properties are the best. When sintered in Ar or N2, the O_2 and N2 in the atmosphere take part in the sintering reaction to break the carbon balance in the cermets to form a shell structure and defects, which results in poor density, microhardness (HV) and transverse rupture strength (TRS).

Processing and mechanical properties of network ceramic/steel composites by pressureless infiltration

A new style Ni-containing alumina ceramic foam based continuous three-dimensional interconnected skeleton was prepared by impregnating a polymeric sponge with aqueous ceramic slurry.Subsequently,alumina ceramic foam/steel metal matrix composites(MMCs) were prepared successfully by sand mold casting technique.The microstructure and mechanical properties of MMCs were investigated by SEM,EDS and compressive test.The results show that the depth of infiltration is about 40 μm to the bonding interface of ceramic/steel and the fracture strength σmax and plastic strain limit εp of composite are 520 MPa and 11.2%,respectively.The fretting wear mechanism of MMCs is mainly performed at the oxidative wear mode with lower load/friction frequency and the predominant oxidation wear together with slight adhesive wear and abrasive wear multiple mode with higher load/ friction frequency.Moreover,the infiltration bonding and continuous three-dimensional interconnected ceramic skeleton play a vital role in the stability of the bonding interface and excellent mechanical properties.

Research on the cutting performance and the wear mechanism of the cermet cutter in high speed turn-milling

When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble cooling fluid, the wear performance of the cermet cutter is bad, and does not adapt to the requirements of machining. However, when machining D60 by high speed turn-milling is under dry conditions, the wearing performance of the cermet cutter is very good and the cutting time lasts almost 3 hours. The wear mechanism of the cermet cutter under the water soluble cooling fluid is different from the dry condition. With the water soluble cooling fluid, a great deal of little chap units are formed since high frequency alternates heat stress. The crash and desquamate of these chap units is the main cause of the cutter wearing. Under dry cutting conditions, it is the main cause of cermet cutter wear in the felting phase intenerating causing rigid phase grains to fall.

Robotic milling for rapid ceramic pototyping

Robotic milling is a developing method for rapidly producing prototypes and parts, but the application is limited for materials such as wax, wood, plastic and light metal, etc. The reason for this is because of the robotic weak rigidity. In this paper, a method of robotic milling for ceramic prototyping is developed, one that has been successfully applied in a new rapid hard tooling technology-Direct Prototype Spray Tooling. At first, the appropriate ceramic materials mixed with metal powder are confirmed for the robotic milling and the following plasma spraying process. Then the 6 - DOF robotic milling paths are extracted from the NC code and transformed into the robotic JBI type file, the NC code generated through the general CAD/CAM software such as UG -NX. Finally, the robotic milling characteristics such as moving path accuracy and milling force are tested to find the best milling parameters and to ensure the executable, accurate and efficient ceramic prototype milling technology. The development of this method not only broadens the robotic milling material range but also extends the rapid prototyping fields. It can also be used for producing ceramic parts that are difficult to machine.

Direct Marketing and Consumer Trust in Organic Food Products： Vilnius （Lithuania） Case

The market of organic food products has a continuous upward trend though the growth rate and sale channels in individual countries are rather different. This research aims to identify the key factors that influence consumers＇ choice to buy organic food products in Lithuania focusing on the consumer trust in the quality and the most acceptable marketing channels. In order to get the necessary information, the residents of Vilnius （the capital of Lithuania）, as having the greatest potential for the organic food market in the country, were interviewed. The analysis of collected data was done using the methods of mathematical statistics and comparison of relative frequencies. The results of this research prove the increasing consumers＇ interest in organic food products. The majority of consumers consider these products to be healthier, better-tasting and fresher. Only about a third of the purchasers （usually buying frequently） can see differences between organic and non-organic products, therefore, there is a problem to distinguish organic food from conventional products and, consequently, remains a possibility to cheat the consumer. An additional quality control and direct sales from known and familiar farmers might increase trust in the quality of organic food products. So far, supermarkets are the most important place to buy organic foods, however, the greater consumer confidence in the quality of organic products bought at farmers＇ markets and the acceptance of the majority of purchasers to buy organic food products directly from the farmers suppose the need to develop a direct marketing system.

Mechanical properties and plasma erosion resistance of BN_p/Al_2O_3-SiO_2 composite ceramics

BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers＇ hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.

Fabrication and Properties of 3Y-TZP/ZrO_2 / Al_2O_3 /MgO Ceramics

Studies on the sintering, microstructure, mechanical properties and low temperature degradation behavior of yttria stabilized-tetragonal zirconia polycrystal （3Y-TZP） were carried out. The results show that the addition of Al2O3 and MgO improve the sintering at low temperatures, and cause exaggerated grain growth and the transformation of tetragonaI-ZrO2 to monoclinic-ZrO2 with corresponding changes in the mechanical properties. The addition of the yttria-free monoclinic zirconia particles change the overall yttria distribution and induce an active transformation toughening mechanism. Furthermore, the dispersed yttria-free ZrO2 can inhibit the tetragonal zirconia transformation, which is beneficial to the improvement of the low temperature degradation behavior of 3Y- TZP ceramics.

Characterization and formation mechanisms of fractures and their significance to hydrocarbon accumulation: A case study of Lower Ordovician mid-assemblage Formations in central Ordos Basin, China

The lower Ordovician mid-assemblage Formations in the central Ordos Basin of China host prolific gas resources,and most hydrocarbon reserves are stored in naturally-fractured reservoirs.Thus,fracture pathway systems may have a significant impact on reservoir performance.This article focuses on the core-and laboratory-based characterization of fractures.Through the developmental degrees,extended scale,output state and filling characteristics of various types of fractures,the results show that there are three distinct fracture types:1)nearly vertical fractures,2)oblique fractures,and 3)horizontal fractures.Based on a systematic study of the characterization of reservoir space,the main geologic setting of natural gas accumulation and the regional tectonic background,type 1 is mainly driven by the tectonic formation mechanism,and type 3 and parts of low-angle fractures in type 2 are induced by the diagenetic formation mechanism.While recovered paleopressure for methane-rich aqueous inclusions trapped in fracture-filling cement indicates that the fracture opening and growth are consistent with gas maturation and charge and such high-angle fractures in type 2 are caused by the compound formation mechanism.The fractures to hydrocarbon accumulation may play a more significant role in improving the quality of reservoir porosity.Furthermore,connected fractures,dissolved pores and cavities together constitute the three-dimensional pore-cave-fracture network pathway systems,with faults serving as the dominant charge pathways of highly pressurized gas in the study area.Our results demonstrate that protracted growth of a pervasive fracture system is not only the consequence of various formation mechanisms but also intrinsic to quasi-continuous accumulation reservoirs.