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In order to improve the wear resistance of aluminum matrix composites and reduce the cost at the same time, the Al2O3/Al composite powder was prepared by hydrothermal method in this experiment, and the material properties of the Al2O3/Al metal matrix composite powder material were studied. It can be seen from the results that the encapsulation degree of Al2O3/Al-based composite powder material first increases and then decreases with the increase of ammonia concentration, and first increases and then decreases with the increase of PH value. The optimal molar ratio of salt and alkali is 1:1. Through the optimization of process parameters, the ratio of aluminum nitrate and ammonia water is obtained as: 1:1, the slurry stirring speed is 1500r/min, the stirring time is 10min, and the heating temperature is 200°C, the obtained composite powder is relatively uniform, has a larger specific surface area, and has better powder properties.

On the one hand, cermet has the advantages of metal materials, and on the other hand, it maintains the excellent properties of ceramic materials, and is a very important new engineering material. In this paper, the alumina/aluminum cermet material composite powder was prepared by ball milling, and its densification properties were characterized and studied to provide reference for the preparation of high-performance cermet materials. When the ball milling time is more than 6h, the distribution of alumina particles around the aluminum powder is relatively uniform. The research shows that: with the extension of the ball milling time, the number of pinning of Al2O3 particles on the surface of the Al ball first increases and then decreases; The trend of decreasing; with the increase of ball-to-powder ratio, the distribution of Al2O3 particles on the surface of Al balls is more uniform. Considering its cost-effectiveness, it is more suitable to prepare pinned alumina/aluminum-ceramic composite powder under the conditions of ball milling speed of 360r/min, ball-to-material ratio of 2:1 and ball milling time of 12h. When the Al content gradually decreased, the density and hardness of the cermet material also decreased gradually. When the Al content gradually decreased, the density and hardness of the cermet material also decreased gradually. When Al accounts for 75% in the sample, the microstructure is dense and the hardness is higher. When the molding pressure is 20MPa, the unevenness of the surface of the material is greatly relieved, relatively flat, and the densification effect is better. When the sintering temperature is 800°C, the fired sample is very dense, and the particles have relatively high bonding strength, but a small amount of aluminum is precipitated on the surface of the sample, forming a silver-white spherical substance.

With the popularization of electricity, the use of electric porcelain is becoming more and more extensive, but in the process of production, the waste of electric porcelain continues to accumulate and increase, which not only pollutes the environment but also affects the normal life of human beings. Therefore, it is urgent to deal with these electric porcelain wastes. In this paper, the electric ceramic waste is used as the main raw material, and starch and kaolin are added to optimize the formula to prepare porous ceramsite. The effects of the content of electrical ceramic waste, sintering temperature and holding time on the properties of porous ceramsite were studied. After research, the results show that with the increase of waste content, the porosity and water absorption first decrease and then increase, while the compressive strength first increases and then decreases. With the increase of the sintering temperature, the porosity and the water absorption rate decrease continuously at the beginning, and the compressive strength increases continuously at the beginning, but when the sintering temperature increases continuously, there will be a turning point or a flattening point. With the continuous extension of the holding time, the water absorption and porosity continue to increase, while the compressive strength continues to decrease, but the overall change is small. The optimization can be found that when the waste content is 75%, the sintering temperature is 1200 °C, and the holding time is 30 min, the prepared porous ceramsite has the best performance. Its water absorption rate: 13.87%, porosity: 27.52%, compressive strength: 20.06MPa.

In view of the low performance of porous ceramics on the wall, the heavy task of saving clay resources, and the major problems of dredging the Yangtze River, this thesis uses low-grade quartz sand along the Yangtze River as the main raw material and kaolin as the plasticizer. Drying, sintering and other processes prepare high-performance porous quartz ceramics, and improve the performance of porous quartz ceramics by studying the control conditions and the control mechanism related to the performance of the sintered body. Quartz porous ceramic bodies were sintered at 1100 °C and 1200 °C, and no obvious gradient structure was found. However, the quartz porous ceramic bodies had obvious gradient structures after sintering at 1300°C. The quartz porous ceramic bodies were sintered. When the temperature is 1400 °C, the green body is not found to have a pore gradient structure. When the water-to-material ratio is 1.2 and 1.3, the quartz porous ceramic body has no obvious gradient structure; when the water-to-material ratio is 1.4, 1.5, the sample has an obvious gradient structure. Combining the cost performance between material performance and energy consumption, in order to obtain a better bonding point, porous silica ceramics should be prepared with a water-to-material ratio of 1.4 and a sintering temperature of 1300 °C to prepare porous silica ceramics with a better pore gradient structure. Its porosity is 32.45%, and its compressive strength is 5.23 MPa.

As a kind of sponge city water-permeable material, permeable brick has good water permeability, chemical stability, corrosion resistance and weather resistance. Therefore, the development of permeable brick also broadens the engineering application market for its application. The discharge of a large amount of manganese slag will cause serious environmental pollution, and the problem of manganese tailings accumulation is serious. There is no ideal treatment method at present. In this paper, manganese tailings slag is used as the main raw material to prepare sponge city permeable bricks, thereby turning waste into treasure. Through research, the permeable brick with MgO used as sintering aid has very low compressive strength and good water permeability. CaO used as a sintering aid has high compressive strength and low water permeability. The porosity and water permeability of permeable bricks increase with the increase of CaCO3, but the compressive strength is opposite. In comparison, the permeable bricks prepared with three different sintering aids, 3% CaCO3 and 2% MgO as sintering aids have good water permeability and superior compressive strength. The permeability coefficient of the permeable brick prepared with 3%CaCO3 and 2%MgO as sintering aids is 2.0×10-2cm/s, and the compressive strength is 1.3MPa.

Nano-SnO2 is a relatively important semiconductor material. Its crystal structure is unique rutile type. It has the advantages of high conductivity, high transparency and stable chemical properties. It is widely used in gas sensing detectors and solar cells for photoelectric conversion. Applications. In this paper, SnO2 nanofilms with different crystal structures were prepared by changing the three process parameters of salt concentration, reaction time and hydrothermal temperature in hydrothermal method. The samples were tested by scanning electron microscopy (SEM) and three-dimensional ultra-depth microscopy analyzer. As the concentration of the reaction solution increases, the macroscopic thickness of the film gradually thickens, and the three-dimensional structure of the surface changes from flat to coarse to coarse peak. The peak between the peaks first increases and then decreases, and the surface microstructure is The conditions change are not obvious. Through the comprehensive comparison of film integrity and surface area, it is found that the concentration is 0.03mol/L, which is relatively better.

Both alumina and boron carbide have good hardness and strength, and are widely used in production and life, industrial manufacturing, and military defense. However, due to the insufficiency of research at this stage and the lack of technical means, it is difficult to prepare alumina-boron carbide composite powder with good coating and ultra high strength through large-scale batch production. Therefore, this experiment wants to obtain a relatively good performance of coated Al2O3/B4C cermet by hydrothermal method through different experimental parameter ratios. Through the experimental results and analysis, the following conclusions are obtained. The most suitable concentration of aluminum nitrate is 0.1 mol/l. The low concentration affects the formation of alumina particles. The concentration is too high and prone to agglomeration. Through the optimization of hydrothermal synthesis concentration, a composite of Al2O3/B4C composite with good nanoencapsulated structure was obtained. The composite powder was pure in composition and high in specific surface area, which lays a foundation for solving the low-temperature preparation of high-density boron carbide ceramics.

YAG materials have a number of unique properties, the application is very extensive. In order to improving the properties of YAG porous materials, the effect of forming processing on the properties of YAG porous ceramics is investigated. Through the results and analysis, the conclusions showed that the porosity of YAG porous ceramics gradually decreased with the molding pressure increases, and the compressive strength of YAG porous ceramics shows a rising trend. The size and number of pores in the microstructure are reduced with increasing the forming pressure, there are inherently many voids in the YAG porous ceramics body at low forming pressures. The porosity of YAG porous ceramic decreases with the increase of dwell time, however, the process of extending from 5 min to 10 min is much faster than the rate of descending from 10 min to 15 min. The size and number of pores in the microstructure are reduced with extending the holding pressure time, which also makes YAG porous ceramics pose the higher mechanical strength. Through the analysis of the results, when the forming pressure is 10MPa, the porosity of YAG porous ceramics is 41.11% and the compressive strength is 5.8MPa, the porosity and compressive strength of YAG porous ceramics is better.

In order which aim to save land resource and use low grade nature resource to realize high cost performance product. In this paper, the molding method of quartz sand fired brick is discussed. As the plastic (hand pressing) is only used to manually beat the mud mass, the sludge is squeezed by hand. Into the mold and molding and cold isostatic pressure molding pressure of 100 MPa, The difference is far away, which makes the gaps between the particles close to each other greatly different, the pressure of hand-press molding is small, the voids in the blank after molding are large and the hole diameter is large, and the green compact density of the brick body is small. The compact densities of the 65MPa and 150MPa pressed brick bodies are all lower than 100MPa, but 150MPa is still denser than 65MPa. The compressive strength is first increased and then decreased with increasing the molding pressure, when the pressure is 100 MPa, the maximum compressive strength is achieved at 100 MPa achieves the highest point.

Dense 3Y-ZrO2composite ceramics were prepared by using 3Y-ZrO2nanopowders as the raw materials, via the process of ball milling, granulating, molding and calcination.We investigated the microstructure, surface morphologies, the mechanical property, the density and linear shrinkage rate of the sintered ceramics and the effect of the ball milling technics and the sintering technics on the above properties of the3Y-ZrO2composite ceramics via SEM and testing. The results show that the most excellent technics in all was explored as follows: the ultrafine ball milling by adding zirconium balls of 2 mm at the speed of 35 r/min for 10 h, with the mass ratio of zirconium ball, water and mixed powders of 6:1:1, the granulaing with 1.5% PVA, the CIP, the pre-sintering to remove the organic substrate to 500°C and the microwave sintering from 20°C to 1450 °Cin 80 min in which the duration at 1450°C was 20 min and the natural cooling time of the samples was 90 min. And the 3Y-ZrO2composite ceramics obtained by this process have a relative density of 99.2%, bending strength of 1098 MPa, and a fracture toughness of 7.8 MPa·m1/2.

Given the shortage of energy reserves, new energy sources must be identified. In this regard, improving the efficiency of solar cell conversion and simplifying the solar cell technology have become the focus of research. In this study, tin oxide nanometer thin film was fabricated on FTO conductive glass as photocathode through hydrothermal method. The synthesis condition was regulated, and performance test was also conducted. Results show that the crystallization driving force, crystallization rate, and grain size of tin dioxide crystal increase with increasing alkali ratio, leading to disorganized accumulation of tin oxide. Under prolonged holding time, tin oxide crystal became complete, and the surface area of the crystal increased. The crystallization driving force and rate also increased with increasing salt concentration and accompanied by clutter of tin oxide. The optimized process condition included 1:4 molar ratio of salt to alkali, 0.05 mol/L salt concentration, 200 °C reaction temperature, and 8 days of reaction. The highest specific surface area of the tin oxide nanometer film was obtained under the optimized condition.

YAG materials has a number of unique properties, the application is very extensive. In this paper, the superfine YAG powder materials were prepared by hydrothermal precipitation method. The influence of synthesis process on the morphology of the powder was investigated. The results showed that when the molar ratio of salt to alkali that Y3+: OH- is 1:8, the more uniform morphology of the particles can be prepared, when the molar ratio of salt to alkali is increased, the morphology of the particles will not change. The reaction time is longer, the particle size will be thicker. The smaller the concentration of Y3+ ions is, the larger the particle size will be small. The experimental results show that the rod-like particles have a poly-crystal structure at the reaction temperature of 200°C, reaction time of 2 days and the molar ratio of salt to alkali of 1:8. The diameter of the rod-like particles is most of the powders have a particle size of 1000 nm and a small amount of powder has a particle size of about 5000 nm. The purity of powder is higher through the test of XRD.

Cermet includes the excellent properties of ceramic materials and the advantages of metal materials, so it is an important new engineering material. In this paper, Al2O3-Al cermet is prepared using different molding process via the powder metallurgy method to study the properties of Al2O3-Al cermet. The conclusion are shown the increasing density of Al2O3-Al cermet is not obvious with increasing the forming pressure of cermet body during the initial and late processing, but the increasing density is more obvious under the forming pressure for 20-30MPa. The density of cermet materials are increased with prolonging holding pressure time, the initial increase speed is faster, and the later growth rate becomes weaker. When the molding pressure is 30MPa, the holding time is 10min, the sintering temperature is 900°C, the holding time is 1h, the prepared Al2O3-Al cermet adding sintering aids has a coated microstructure, which indicates that the large number of particles is migrated on the grain boundary. The sample density is 2.26g/cm3, the density is highest, the distribution of Al2O3 and Al phase is the most uniform. The buried sintering method is more suitable for the preparation of Al2O3-Al cermet composites than the nudity sintering method.

This work investigated the effects of molar ratio of salt to alkali on the properties of tin oxide nanofilms to provide reference for optimizing its photoelectric conversion efficiency. The tin oxide film grown by hydrothermal method exhibited poor film-forming property. The macroscopic analysis revealed the formation of a thick film. The bonding force to the FTO substrate was poor, its brittle, and easy to fall off. When the molar ratio of salt to alkali was 1:8, the tin oxide film exhibited improved microstructure and large specific surface area, which could benefit electron transport. Moreover, the film showed excellent photoelectric conversion performance. However, mechanical properties, such as adhesion between the tin oxide film and the conductive glass FTO, remain to be improved.

To provide reference for optimizing the photoelectric conversion efficiency, we studied the effects of salt–alkali molar ratio on the properties of tin oxide nanofilms. We found that when the hydrothermal temperature was increased to 80 °C, the film growth was not complete. With a hydrothermal temperature of 120 °C, the film became more complete and structured. However, at 160 °C, thick and very irregular tin dioxide (SnO2) crystal particles were deposited on the FTO conductive glass surface. With the increase in heat treatment temperature, crystallization became more and more dense and complete. At 80 °C hydrothermal temperature, the simulated peak of the surface and number of peaks became smaller. However, they significantly increased with a hydrothermal temperature of 120 °C. When the hydrothermal temperature was at 160 °C, the surface simulated peak increased, but the number of peaks decreased. Moreover, the diameter of each peak was greatly increased. The film obtained via the hydrothermal method was relatively pure, and Sn(OH)3 was not completely converted into SnO2.

Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, Al-Al2O3 cermet is prepared adding different sintering aids via the powder metallurgy method to study the properties of Al-Al2O3 cermet. The conclusions are shown the adding sintering aids can significantly improve the sintered density of Al-Al2O3 cermet. The sintering aiding effect of adding MgO is better than that of SiO2 and Y2O3, and the hardness and the strength of the sample are higher than those of samples with SiO2 and Y2O3, and the densification degree of Al-Al2O3 metal ceramic material is the best, the relative density is 94.8%, the surface hardness is 824HV. The flatness of the surface of the sample adding MgO shows that the bonding strength between aluminum powder and alumina powder is high. The prepared Al-Al2O3 cermet adding different sintering aids have higher density and fewer pores in the microstructure the prepared Al-Al2O3 cermet adding sintering aids has a package structure.

Alumina ceramics with good mechanical and corrosion resistance are the ones of the most widely used engineering ceramics. The aluminum has high strength, high conductivity and high plasticity etc. so that aluminum ceramics are used in more and more industries. In this paper, the mass fraction of 25% Al2O3 powder and the mass fraction of 75% Al powder were mixed in the blender. Mixer speed is100r/min with mixing time of 3.5 h. Forming, sintering and a series of processes for preparing the alumina/aluminum metallic ceramic materials, through performance testing and analysis, found that the density of the sample firstly increased and then decreased with the increase of sintering temperature. A melting point is close to the sintering temperature and the density of the cermet can be made relatively high. When the sintering temperature is about 600°C and 700°C, the macro performance of sample is better. The cermet is sintered at 700°C and its microstructure is relatively better.

YAG materials have a number of unique properties, the application is very extensive, the burn is due to the temperature is too high or the residence time at high temperatures is caused. The undercurrent is the sintering temperature is too low or the holding time is not enough, resulting in product performance is too low or too small shrinkage. In this paper, the effect of sintering temperature on properties of YAG porous ceramics was investigated. The results showed that the firing temperature of the ingredients will be different and cause the same sintering process and sintering additives content of different samples burned. The increase in the content of SiO2 in the furnish with the sintering aid tends to occur. the effect of temperature on the mechanical properties of the samples after sintering was significant, so the raw materials include 60wt%YAG, 10wt% CaO, 10wt% SiO2 and 20wt% soluble starch, the molding process in 20MPa pressure 10min, the sintering at 1500°C for 2h, the sample porosity is 42.2%, the compressive strength is 5.8MPa, the outside shape is keep intact and the better pore microstructure is shown.

Ultrafine SnO2 is a new type of material, in the field of solar cells and semiconductors have a lot of use. To get different morphology and different properties of tin oxide powder material, making more applications in the field, the effect of the adjuvants on the properties of superfine SnO2 powders were distigated. Through the analysis of experimental results, the conclusions are shown the stronger the alkalinity of the auxiliary agent, the larger the grain size of the obtained particles and the more uniform the particles. When the molar ratio of salt to alkali is more than 1: 4, the amount of alkali is gradually reduced, the particle size is small, the morphology is not uniform and easy to agglomerate. When the molar ratio of salt to alkali is 1: 4, the smaller particle size is shown, the appearance morphology is uneven. The longer the reaction time, the more complete the grain, the more uniform the morphology. Under the condition of SnCl4 concentration of 0.05mol/L, reaction time is 4 days, salt and alkali molar ratio is 1: 4, holding temperature is 200°C, the auxiliary agent is NaOH, the size, shape and performance of synthesized SnO2 are the better.

The YAM coatings on the ZrB2 composites surface were prepared by co-precipitation technique and with Al (NO3)3 and Y(NO3)3 solutions acting as precursor. The effect of matrix surface treating conditions, dipping times and calcination temperature was investigated. Phase compostion, coating morphology and interface between matrix and coating were analyzed by XRD and SEM. The results indicated that the YAM coating was formed after calcined at 1250°C in vaccum. The thickness of coating was increased with the dipping times, the smoothest coating was obtained by two dipping times, and matrix surface coarsing was beneficial for improving the adhension between matrix and coating. The ablative teste was evaluated at 2000°C by oxy-acetylene flame, the ablative properties was obviously improved by coating compared with uncoated composites.

In atmospheric environments, Al2O3 ceramics have good oxidation resistance in water, acid, and other solutions and suitable corrosion medium resistance. Al2O3 ceramics is one of the most widely used engineering ceramics. In this paper, Al2O3/Al cermet matrix composites were prepared by mixing a series of powders with aluminum and alumina powders as raw materials. The interface of Al2O3/Al cermet was observed by scanning electron microscopy. The densification process of Al2O3/Al cermet was then explored from the aspects of formulation, molding pressure, holding time, and sintering process. After mixing and dry pressing, 50 wt% Al and 50 wt% Al2O3 were appropriate for sintering. Following sintering and measuring density, density was improved under 20 MPa with a 20-minute holding time. Through a comparison of the sintering process, the interface structure was observed via scanning electron microscopy, which found that secondary sintering is conducive to improving the density of Al2O3/Al cermet.

YAG materials has a number of unique properties, the application is very extensive. In this paper, the superfine YAG powder materials were prepared by co-precipitation method and hydrothermal precipitation method. The influence of synthesis process on the morphology of the powder was investigated. The results showed that the precursor powder prepared via the co-precipitation method is mainly from amorphous to crystalline transition with the increasing calcination temperature, the precursor agglomeration is more serious, In the process of increasing the calcination temperature, the dispersibility of the roasted powder is greatly improved, which is favorable for the growth of the crystal grains, so that the particle size of the powder is gradually increased, the YAG precursor prepared by the co-precipitation method is transformed into YAG crystals, the phase transition occurs mainly between 900 and 1100°C. When the molar ratio of salt to alkali is Y3+: OH-=1: 8 via the hydrothermal reaction, the YAG particles with homogeneous morphology can be obtained. When the molar ratio of salt and alkali is increased continuously, the morphology of YAG particles is not obviously changed. The co-precipitation method is easy to control the particle size, the hydrothermal method is easy to control the particle morphology.

Ultrafine Co2O3powder was prepared via hydrothermal synthesis. The effect of technology on the performance of the superfine Co2O3powders was investigated, and the hydrothermal parameters in preparing Co2O3were gradually improved. In addition, the morphology and grain size of the Co2O3powder were analyzed by FESEM. Results show that reducing the salt–alkali molar ratio resulted in more uniform Co2O3powder and smaller particles, with average particle size of approximately 40 nm. Reaction time displayed little effect on the Co2O3powder, but the particle size decreased with the reaction time. The concentration of salt solution remarkably affected the morphology of the Co2O3powder. Lower concentration resulted in smaller particle aggregation and particle size.

Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, Al-Al2O3 cermet is prepared using different molding process via the powder metallurgy method to study the properties of Al-Al2O3 cermet. The conclusions are shown the density of the initial and late increase is not obvious with the cermet body forming pressure increases, but the increase in density of 20-30MPa is more obvious. The density of the cermet material increases with prolonging holding pressure time is shown, the initial increase speed is faster, and the later growth rate becomes weaker. In the different molding pressure, the pressure is 40MPa and 15min, sintering temperature is 700°C and 1h, the sample density is 2.084g/cm3, the highest density, the best performance, aluminum and alumina distribution is the most uniform.

The sintering methods of quartz sand porous ceramics were researched with the low grade quartz sand along the Yangtze River via the vacuum sintering method in this paper, which lay technology foundation for researching new heat insulating materials. The quartz porous ceramics is obtained with the high performance cost, the quartz porous ceramics is sintered at 1050°C via the vacuum conditions, the density of ceramics is 1.267g/cm3, the porosity is 51.6%, the compressive strength is 3.184MPa, the porous ceramics show the homogeneous distribution micro-pore and good shape. The density and the compressive strength of prepared ceramics via the vacuum sintering both are higher than that of prepared ceramics via the atmosphere sintering, however, the porosity is shown the opposite results.

Zirconium diboride is widely applied because of some excellent performances. The oxidation kinetics of ZrB2-YAG-Al2O3 composite materials were researched, which helps to improve the performance of ultra-high-temperature composite materials. The results show the oxidation weight gain is decreased with increasing the content of YAG-Al2O3 and the molar ratio of Al2O3. The oxidation weight gain is increased with prolonging the oxidation time under 1300°Cæ, the oxidation weight gain ratio is decreased with prolonging the oxidation time. The effecting tendency of oxidation weight gain is not abvious with varying the contend of YAG-Al2O3 upon 1300°Cæ, however, the effecting tendency of oxidation weight gain is very abvious with varying the molar ratio of Al2O3.

The composite ZrB2 powder coated A12O3-Y2O3 prepared by co-precipitation method were densified via the spark plasma sintering (SPS) and then researched the oxidation resistance at high temperature. ZrB2 powder must have the better dispersibility during the coating processing for obtaining the better coating effect. Effect of dispersant on the dispersibility of ZrB2 powder in the liquid is researched in this paper, the results show ZrB2 powder have the better dispersibility as the dispersant for PMAA and the content for 2vol%, which lay foundation for synthsising the better coating effect coated A12O3-Y2O3-ZrB2 composite powder.

Cermet materials is a important new engineering materials with the advantages of ceramics and metal materials. The Al2O3/Al cermet materials is prepared via the powder metallurgy method, the effect of sintering technology on properties of Al2O3/Al cermet materials is researched in this paper, which lay the base for preparing the high performance cermet materials. The results are shown through the study, the denstity of cermet is increased with an increasing moliding pressure, the sample density is 2.084g/cm3 as the pressure for 40MPa and the sintering temperature at 600¡æ, the density is higher, that is to say it is highest performance, the distribution of aluminum and alumina is most uniform. When the sintering temperature is higher, howerver, the molding pressure is lower, the lower density of the sample is shown, the aluminum is easier to overflow the surface of the sample.

Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, prepared by calcination of alumina - aluminum metal-ceramic composite material powder, and its characterization as a basis to provide raw materials for preparing high performance metal ceramic material. According to the research, with the calcination temperature is increased, the rate of change gradually increase the weight of aluminum. Calcined at a temperature of 600¡æ, the oxidation of aluminum surface the best. With the firing time increases, the rate of change in the weight of aluminum powder showed an increasing trend. When 8h, oxidation of aluminum surface better. Through this experiment, process optimization can be found in the calcination temperature was 600¡æ, calcination time is 8h, the best coating effect aluminum surface, coating evenly, clean interface, the reaction layer thickness of about 700nm, the prepared package type composite powders the best results.

Porous quartz ceramics were produced using river sand from the Yangtze River in China as the raw material by the use of sponge absorption methods. We found that sintering conditions clearly affected the porous structure and other properties. With increasing sintering temperature, the microstructure of the samples changed accordingly and the density increased while the porosity decreased, the micropore edges gradually became smooth. The density of the porous quartz ceramics increased at a holding time of up to 60 min but the porosity decreased. Optimum sintering of the porous quartz ceramics was obtained at 1 100 °C over 60 min as determined by an analysis of the performance–price ratio of the porous quartz ceramics, the density is 1.25 g cm–3, the porosity is 49.5 %, the outside shape is regular, the micropore structure is smooth.

ZrB 2 belongs to a class of ceramics defined ultra-high-temperature ceramics with extremely high melting temperatures; however, ZrB 2 ceramics is easily oxidized. To make ZrB 2 ceramics possess the better oxidation resistance in the air at high temperature, in this paper, the effect of surface modification on the properties of YAG– ZrB 2 ceramics were investigated. Fracture toughness of sintered ceramics with coated raw materials is higher than that of sintered ceramics with mixed raw materials under the same phase and phase content conditions. Oxidation layer thickness of sintered ceramics with coated raw materials is thinner than that of sintered ceramics with mixed raw materials. The results indicate that the sintered coated structure ceramics with coated raw materials help to increase the mechanical property and oxidation resistance of YAG– ZrB 2 ceramics.

ZrB 2 are widely applied because of some excellent performances; however, ZrB 2 is easily oxidized in the high-temperature air. To reach better Al ( OH )3– Y ( OH )3 composite shell and higher coating ratio on the ZrB 2 particles surfaces, ZrB 2 particles must be adequately dispersed in the ZrB 2 suspension during the coating process. The dispersion of ZrB 2 particles and the influence of dispersion on coating effect of ZrB 2@ Al ( OH )3– Y ( OH )3 core-shell composite particles were investigated. The dispersion of ZrB 2 suspension adding the polyelectrolyte dispersant is better than that of ZrB 2 suspension adding the nonionic dispersant; the dispersant content is 2 vol% of ZrB 2 suspension to reach the best dispersion. The best dispersion is obtained by the ultrasonic dispersion for 10 min. ZrB 2 particles are coated using the dispersant and the ultrasonic dispersion in the ZrB 2 suspension to obtain the better coating effect. The dispersion of ZrB 2 particles is increased with increasing the coating content.

Silicon nitride ( Si 3 N 4) has attracted substantial interest because of its extreme chemical and physical properties, but the sintering densification of Si 3 N 4 is difficult, and it is easily oxidized in the high-temperature air to impact high-temperature strength, which restricts its applied range. In order to decrease the oxidization and improve the strength of Si 3 N 4 at high temperature, the surface of Si 3 N 4 is coated with Al ( OH )3 and Y ( OH )3 to synthesis Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite particles. Through TEM, XRD, and BET analysis, when pH is about 9, Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite particles are successfully synthesized by co-precipitation methods. Coating layer is about 200 nm, which is compaction and conformability. Dispersion of coated Si 3 N 4 with Al ( OH )3 and Y ( OH )3 particles are very good. Synthesis of Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite powder will lay the foundation for preparing high-performance YAG/Si 3 N 4 multiphase ceramic materials.

Although Zirconium diboride ( ZrB 2) is a desirable combination with some good properties, it is easily oxidized in the high-temperature air to impact high-temperature properties, which dwindles the applied range. In order to decrease oxidization and improve the high-temperature properties of ZrB 2, the surface of ZrB 2 is coated with Al ( OH )3– Y ( OH )3 to synthesize Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles. In this paper, the conditions of synthesizing Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles by the co-precipitation method are investigated. Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles are synthesized under different conditions, but the conditions of synthesizing Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles with the better coating quality require pH = 9, the appropriate concentration ( Al 3+ = 0.017 mol/L , Y 3+ = 0.01 mol/L ) of composite solution, reaction time of 60 min, titration speed of 0.05 ml/s, using the dispersant in the ZrB 2 suspension and the ultrasonic dispersion, respectively.

Although ZrB 2 has some excellent performances, it is easily oxidized in the high-temperature air, which is deadly shortcoming as high-temperature materials. To increase the high-temperature performances of ZrB 2, Al 2 O 3 and Y 2 O 3 particles are coated on the ZrB 2 surface to prepare ZrB 2– Al 2 O 3– Y 2 O 3 composite particles. The oxidation resistance mechanism of ZrB 2– Al 2 O 3– Y 2 O 3 composite particles is investigated by DTA-TG, TEM, and XRD. The surface of ZrB 2 particle is coated with compact Al 2 O 3 and Y 2 O 3 particles, which establishes the foundation to attain good oxidation resistance. ZrB 2 particle is mainly oxidized to increase the weight, from 600°C to 800°C. B 2 O 3, obtained through the oxidization reaction, might coat on the surface of ZrB 2 particle to retard the oxidization reaction, which further increases the oxidation resistance. The oxidation resistance of coated ZrB 2 particle is far better than that of original ZrB 2 particle.

Zirconium diboride is widely applied to high-temperature materials, but it is easily oxidized at high temperature. To increase the oxidation resistance of zirconium diboride at high temperature, the A 1( OH )3– Y ( OH )3 is coated on the ZrB 2 surface to prepare A 1( OH )3– Y ( OH )3/ ZrB 2 composite particles. In this paper, the effect of coating content on the properties of A 1( OH )3– Y ( OH )3/ ZrB 2 composite particles is investigated. It is analyzed that the particle size and particle size distribution of A 1( OH )3– Y ( OH )3/ ZrB 2 composite particles is increased with the coating content. The dispersion of ZrB 2 particles is largely increased with the coating content of 0%–20%; the dispersion of ZrB 2 particles is similar when the coating content is from 20% to 30%. The oxidation resistance ratio of the ZrB 2 particles with 30% coating content is the best than that of other conditions—it is about three times more than that of the original ZrB 2 particles.

With the fast development of new materials investigation, attention is paid to. The performance of superfine powders, which must be modified on the surface to acquire some points. Coating technology of particles is one especial method of surface modification. In this paper, coating methods of particles are classified into solid state, liquid state, and gaseous state, main methods and mechanisms during current time are reviewed, respectively, and some research examples are listed. The choice of diversified coating technologies is decided synthetically based on powder materials, performance of the modified substance, and application of coated powders. In the future, the researches of the core-shell modification mechanism, coated particles with an ordered arrangement coating layer, a new surface active agent, the facilities of suiting surface modification, and the evaluation methodology of the surface coating effect are very exigent and necessary for the preparation and application of superfine powders.

ZrB 2 has some excellent performances, but it is easily oxidized at high temperatures to impact the high-temperature strength, which restricts its applied range. To protect from the oxidization and improve the strength of ZrB 2 at high temperature, the surface of ZrB 2 particles is coated with the Al ( OH )3– Y ( OH )3 shell to synthesize ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles. Through the thermodynamic and kinetic analyses of the heterogeneous nucleation and homogeneous nucleation, the concentration product of precursor ion ( Y 3+ or Al 3+) and OH - (Qi) must be greater than the solubility product (K sp ), respectively; the conditions of Y 3+ and Al 3+ are reached to produce Al ( OH )3– Y ( OH )3 shell on the ZrB 2 surface between the Y 3+ line and the AlO 2- line. Through TEM and XRD analyses, ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles are successfully synthesized by the co-precipitation method, the shell layer quality is better at pH = 9, which established the foundation for preparing high-performance YAG / ZrB 2 and Al 2 O 3– YAG / ZrB 2 multiphase ceramic materials.