Mullite Content Research Articles

The Influence of Mullite Shape and Amount on the Tribological Properties of Non-Asbestos Brake Friction Composites

For investigating the effect of mullite as a reinforced fiber of the non-asbestos brake friction material on the performance of brake pads, mullite reinforced composites with different contents (5% and 10%) and shapes (powder-based and fiber-based) were developed, and the physical and mechanical properties of the composites were analyzed. The tribological properties of the composites were tested by a Chase tester followed by the IS-2742 standard, and the worn surface was investigated by three-dimensional surface topography and SEM. The results show that the brake friction material with 5% powdered mullite performs best, having the highest stable friction performance (0.86), the lowest wear rate (3%), the lowest friction variation performance (0.263), and the best fade-recovery performance. With the increase of mullite content, the friction variation, wear resistance, and friction stability of the composites become worse. Meanwhile, the performance of powder-based mullite composites is better than that of fiber-based. The worn surface analysis shows that the fiber-based mullite composite has a higher surface roughness, fewer contact platforms, more wear debris, and peeling pits. In contrast, the powder-based mullite composites have a better surface performance. It provides a practical basis for mullite-reinforced non-asbestos brake friction materials.

Recycling of aluminum dross and silica fume wastes for production of mullite-containing ceramics: Powder preparation, sinterability and properties

The improper disposal of industrial wastes causes environmental pollution so their recycling for fabrication of new products became an interesting research issue. In this work, sintered mullite-containing ceramics were prepared from aluminum dross and silica fume (up to 40 wt%) waste materials after sintering up to 1500 °C. Before sintering, the starting waste materials were converted into nano powders by mechanical milling alloying method up to 15 h. The obtained waste nano powders were investigated using different techniques as X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). On the other hand, phase identification by XRD, physical properties determination (bulk density and apparent porosity), microstructure by SEM, mechanical and electrical properties of sintered bodies were investigated. The results revealed that mullite phase was formed in higher amounts with increasing both sintering temperature (1500 °C) and silica fume content. At 1300 °C, amorphous mullite was formed in addition to the alumina phase. It is also noted that the apparent porosity and bulk density were reduced with increasing silica content. However, they exhibited opposite trend when the temperature increased from 1300 into 1500 °C. Moreover, with increasing the mullite content, the microhardness, compressive strength, Younges modulus and electrical conductivity were decreased and reached 10.2 GPa, 216.9 MPa, 119.7 GPa and 4.9 × 10 −12 S/m, respectively, for the sample that contained higher amount of mullite, while the fracture toughness was improved and reached to 3.44 MPa m0.5.

Study of aluminosilicate refractories after operation in the presence of fluorine-containing wastes

Samples of aluminosilicate refractory after operation in the shaft and in the hearth of a coke-gas cupola were investigated; this cupola was used for smelting of cast iron with spheroidal graphite using carbon wastes from aluminium electrolysis production as a reducing agent. Use of only fluorine-containing carbon wastes as a solid fuel in cast iron production allows to utilize hazardous man-caused wastes, improves the economic performance of production and has influence on resistance of fireclay refractories. It was established that the products acquire a distinct zone features during the service, due to penetration of the components of gas and liquid phases and the effect of low-boiling components of carbon-containing wastes. Upon that, changes in the structure along the distance from the working space are complex ones in lining thickness and in concentration of volatile components in the “cold” parts of the lining. Permanent character of the mullite content in different zones of fireclay products can be traced, as well as a slight increase in the less altered zone, despite the different service conditions. Absence of alkaline and fluoride phases in the zones of refractory products in the pores and structure of the fireclay refractory was established, due to migration of these gaseous phases into the working space of the cupola with their subsequent removal with furnace gases. Additional development of mullite in certain zones of refractory was revealed, resulting by its synthesis from alumina that did not react during fireclay refractories manufacture under the mineralizing action of a fluorine compound. Use of fluorine-containing carbonaceous wastes as a solid fuel in cast iron production makes it possible to utilize hazardous man-caused wastes, improves the economic performance of production and has slight effect on resistance of aluminosilicate refractories in the conditions of a coke-gas cupola.

The Mechanism of Porcelain Toughened by Activated Kaolinite in a Lower Sintering Temperature.

A high sintering temperature is usually required to acquire excellent performance in the ceramic industry, but it results in high fuel consumption and high pollution. To reduce the sintering temperature and to toughen the porcelain, a self-produced sintering additive of citric acid activated kaolinite was added to the raw material; X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and thermal gravity analysis and differential scanning calorimetry (TG-DSC) were used to characterize the samples, and the toughening mechanism was discussed. The citric acid activated kaolinite obtained high activity and a large specific surface area. After introducing the activated kaolinite, the bending strength of porcelain at 1270 °C increased from 100.08 MPa to 124.04 Mpa, which was 11.45% higher than that of porcelain without activated kaolinite at 1350 °C. The results of XRD revealed that the content of mullite increased and the quartz decreased at 1270 °C, and the well-distributed needle-like mullite was observed in the images of SEM with the addition of citric acid activated kaolinite. The TG-DSC results indicated adding activated kaolinite to porcelain raw materials reduced the formation of mullite to 994.6 °C. The formation of mullite in a lower temperature served as mullite seeds in a green body during firing, and it enhanced the growth of mullite. These contributed to the appropriate phase composition and the excellent microstructure of porcelain. Thus, the distinguished mechanical performance of porcelain was obtained. Moreover, the sintering additive had no adverse effect on the porcelain body as citric acid-activated kaolinite was one of the main components of the porcelain raw material.

Influence of Ceramsite with Assembly Unit of Sludge and Excavated Soil on the Properties of Cement Concrete.

The application of sludge in the manufacture of ceramic material provides an outlet for waste disposal. In this study, we aimed to produce a new lightweight aggregate applications in concrete. The influence of burning temperature on the ignition loss rate, cylinder compressive strength, and the water absorption rate of ceramsite mixed with sludge and excavated soil was investigated. The slump flow, apparent density, and mechanical strength (flexural and compressive strengths) of cement concrete with ceramsite were determined. Moreover, the chloride ion permeability coefficient and the thermal conductivity were tested. Finally, scanning electron microscopy, X-ray diffraction, and thermal analysis were applied to analyze the mechanisms of the properties of ceramsite. Results show that the ignition loss rate and the burning temperature are in a quadratic relationship. The cylinder compressive strength shows a positive quadratic relationship with the burning temperature. However, the water absorption rate negatively correlates with the burning temperature. The addition of sludge can increase the ignition loss rate and cylinder compressive strength of ceramsite. Meanwhile, the effect of sludge on the water absorption rate is the opposite. Ceramsite decreases the slump flow and the apparent density of cement concrete. Cement concrete with 10% ceramsite shows the highest mechanical strength and the lowest chloride ion migration coefficient. Correction of the chloride ion migration coefficient and the content of ceramsite was performed as an exponential equation. Ceramsite exerts a negative effect on the thermal conductivity of cement concrete. Concrete with sludge ceramsite shows higher slump flow, apparent density, mechanical strength, and resistance to chloride ion penetration and thermal conductivity than concrete sludge with clay ceramsite. The mullite content of sludge ceramsite is higher than that of clay ceramsite. Additionally, sludge ceramsite exhibits a denser structure than that of clay ceramsite.

Mechanical properties of in situ synthesized mullite‐based composite ceramics with three‐dimensional network structure

AbstractNeedle‐like nanocrystalline mullite powders were prepared through the molten salt process at the temperature of 900°C using coal gangue as raw material. Then, mullite‐based composite ceramics were prepared by a conventional solid‐state reaction between in situ synthesized mullite and Al2O3 powders. Effects of Al2O3 content and sintering temperatures on phase compositions, microstructure, and mechanical properties of the mullite‐based composite ceramics were also studied. The results show that mullite content productivity increase from 72% to 95%, as the sintering temperature increased from 1480°C to 1580°C, which led to the improvement in the bulk density and flexural strength of the samples. The three‐dimensional interlocking structure for mullite‐based composite ceramics was obtained by the in situ solid‐state reaction process. The maximum bulk density, flexural strength, and fracture toughness for the sample with 15 wt% Al2O3 content are 2.48 g/cm3, 139.79 MPa, and 5.62 MPa··m1/2, respectively, as it was sintered at the temperature of 1560°C for 3 h. The improved mechanical properties of mullite‐based composite ceramics maybe ascribed to good densification and increased mullite phase content, as well as to the in situ three‐dimensional network structure. Therefore, the results would provide new ideas for high‐value utilization of coal gangue.

Microstructural and mechanical characterization of high strength porcelain insulators for power transmission and distribution applications

Porcelain insulators have prodigious importance in electricity transmission and distribution network because of their high dielectric constant, electrical resistivity, and mechanical strength and these properties are closely connected to the microstructural details of the insulator. Three different porcelain insulators (Sample A, B and C) were reported in the present work. X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), three point bending test and density and pore analysis were carried out to investigate the structural and mechanical properties of various insulators. The analysis confirmed that the porcelain insulators are made of industrial alumina, quartz, clay, and feldspar having amorphous as well as crystalline phase in the body. The porosity, density, and bending strength were also calculated and a correlation was developed between mechanical strength of the insulator and various physio-chemical and microstructural properties. Sample A showed the highest value of bending strength i.e. 207.20 MPa and sample C the lowest value of 112.18 MPa while sample B demonstrated the intermediate value of 170.98 MPa. To formulate high strength porcelain insulators, it was concluded that the amount of amorphous phase, dispersed corundum, and mullite content are key factors to control the mechanical strength of porcelain insulators.

Kinetics Study of Al Extraction from Desilicated Coal Fly Ash by NaOH at Atmospheric Pressure

The most promising source of alumina in the 21st century is the coal fly ash (CFA) waste of coal-fired thermal plants. The methods of alumina extraction from CFA are often based on the pressure alkaline or acid leaching or preliminary roasting with different additives followed by water leaching. The efficiency of the alumina extraction from CFA under atmospheric pressure leaching is low due to the high content of acid-insoluble alumina phase mullite (3Al2O3·2SiO2). This research for the first time shows the possibility of mullite leaching under atmospheric pressure after preliminary desilication using high liquid to solid ratios (L:S ratio) and Na2O concentration. The analysis of the desilicated CFA (DCFA) chemical and phase composition before and after leaching has been carried out by inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The morphology and elemental composition of solid product particles has been carried out by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). An automated neural network and a shrinking core model (SCM) were used to evaluate experimental data. The Al extraction efficiency from DCFA has been more than 84% at T = 120 °C, leaching time 60 min, the L/S ratio > 20, and concentration of Na2O—400 g L−1. The kinetics analysis by SCM has shown that the surface chemical reaction controls the leaching process rate at T < 110 °C, and, at T > 110 °C after 15 min of leaching, the process is limited by diffusion through the product layer, which can be represented by titanium compounds. According to the SEM-EDX analysis of the solid residue, the magnetite spheres and mullite acicular particles were the main phases that remained after NaOH leaching. The spheric agglomerates of mullite particles with non-porous surface have also been found.

Fabrication of high-performance silica-based ceramic cores through selective laser sintering combined with vacuum infiltration

Silica-based ceramic cores have been widely used for manufacturing aero-engine hollow blades due to excellent mechanical properties and chemical stability. In this study, selective laser sintering (SLS) based on 3D printing was combined with vacuum infiltration (VI) to fabricate silica-based ceramic cores. The influence of laser processing parameters and infiltration times on the mechanical properties of the silica-based ceramics was investigated. The results showed that the optimal SLS processing parameters were determined as 11 W, 2000 mm/s and 100 µm for the laser power, scanning speed and hatch space, respectively. Meanwhile, as the infiltration time increased to 120 min, the room temperature flexural strength was gradually improved to 7.45 MPa, while the linear shrinkage was constantly reduced to 0.60%, all due to the enhanced α-cristobalite and mullite content. Furthermore, the high temperature creep deformation and flexural strength at 1550 ℃ of the silica-based ceramics prepared with the optimal SLS processing parameters and infiltration time were 0.31 mm and 15.04 MPa, which meets the need of ceramic cores. Consequently, high-performance silica-based ceramic cores can be fabricated by SLS-VI for the rapid manufacturing of hollow blades.

Optical characterisation of alumina–mullite materials for solar particle receiver applications

Alumina–mullite particles are used in high-temperature solar thermal applications such as solar particle receivers. In this study, optical properties of alumina–mullite materials with variable content of alumina and mullite are determined in the spectral range of 0.193–1.69 μm. Variable angle spectroscopic ellipsometry is performed for alumina–mullite thin films, which are fabricated by magnetron sputtering. The thin films are characterised by scanning electron microscopy, atomic force microscopy, and energy dispersive spectroscopy methods. The B-spline model is employed to generate ellipsometric parameters to fit the measured data and to obtain the optical properties. The investigated materials of variable content of alumina and mullite have a similar refractive index in the considered spectral range. The absorptive index of the alumina–mullite materials in the spectral range of 0.193–0.4 μm is higher than in the range 0.4–1.69 μm. The absorptive index decreases with increasing content of alumina in the spectral range of 0.193–0.4 μm. The material composed of similar proportions of alumina and mullite yields the highest absorptive index in the spectral range of 0.4–1.1 μm. The optical properties determined for the alumina–mullite materials are applied to obtain the radiative properties of spherical homogeneous particles. Mie theory is used to calculate absorption and scattering efficiency factors, as well as the scattering phase function. In addition, the scattering phase functions are obtained using the Henyey–Greenstein approximation and the transport approximation. The Monte Carlo ray-tracing method is employed to study the radiative transfer in a model one-dimensional particle curtain containing polydisperse particles exposed to high-flux solar irradiation. It is found that the overall reflectance, absorptance and transmittance of the particles only weakly depend on the optical properties of the materials investigated.

Factors Influencing Mullite Formation in Refractory Grog

The mineral mullite has many outstanding refractory properties. The content of aluminum oxide in the raw material is the basic factor influencing the content of mullite in the final product. Depending on Al2O3 content, silica-alumina materials can be divided into fireclay and high-alumina with the Al2O3 content of 45 % and more. The study describes the influence of raw material, the influence of homogenization of raw material and influence of firing temperature on the mullite formation in fireclay refractory material. Three kinds of refractory clay with different chemical composition were used as raw material for fireclay grog production. Three kinds of homogenization and three different temperatures were studied as factors influencing mullite formation. Powder X-ray diffraction was used to determine mullite content in material. Quantitative phase analysis was conducted by the Rietveld method. Mullite crystals morphology was observed by scanning electron microscopy.

Comparison of stimulated luminescence properties of various porcelain-based items from Turkey towards prevalent features for retrospective dosimetry

In the present study, different porcelain-based materials including a sugar bowl, an ashtray, a porcelain breaker, an artificial dental implant, an electric fuse and the seal of a porcelain moneybox were investigated via thermally (TL) and optically stimulated luminescence (OSL). For this purpose, luminescence dosimetric properties such as TL and OSL curve shapes, reproducibility, bleachability, along with dose response features such as linearity and lowest detectable dose limits (LDDL) of these materials were compared. A feature that is sample-dependent deals with both quartz and mullite content of each porcelain paste, as it was indicated by XRD analysis. Three dominant peaks in TL glow curves were ubiquitously observed, and OSL decay curves formed in two components (C1 and C2) for all samples. It was determined that the LDDL for only two TL peaks (P1 and P2) seem acceptable for accidental retrospective dosimetry applications (0.9–2.2 Gy). On the other hand, the LDDL values obtained according to OSL analysis yielded more promising results in terms of accidental retrospective dosimetry applications as 0.3–0.4 Gy and 0.75–1.35 Gy for C1 and C2 components, respectively. TL peaks P1 and P2 indicate the majority of prevalent, if not universal, properties of stimulated luminescence. This latter universality could support an argument towards identification of these two TL peaks directly correlated to quartz mineral. On the other hand, TL P3 could be attributed to a contribution of more than one mineral, such as quartz, kaolinite and mullite, due to the lack of prevalence over all stimulated luminescence features.

Effects of micro‐sized mullite on cristobalite crystallization and properties of silica‐based ceramic cores

AbstractSilica‐based ceramic cores are extensively used in investment casting process, during which they must exhibit sufficient flexural strength and deformation resistance. In this study, micro‐sized mullite was used as an additive to silica‐based ceramic cores to optimize their high temperature properties. To investigate the effects of micro‐sized mullite on cristobalite crystallization, mechanical and thermal properties of silica‐based ceramic cores, ceramic cores with different amounts of micro‐sized mullite were fabricated. The XRD results showed that additional micro‐sized mullite diminished the crystallization of cristobalite at high temperatures, primarily caused by the mullite related compressive stresses on the surface regions of fused silica particles. Three‐point bending tests and SEM results showed that micro‐sized mullite had a more significant effect on the flexural strength of ceramic cores compared with conventional additives. Particularly, the fracture mechanism of silica‐based ceramic cores had been changed from intergranular fracture into a mixed fracture consisting of both intergranular and transgranular fracture. The mechanical and thermal properties of ceramic cores were all reduced slightly as the mullite content exceed 4.6 wt%. Hence, to optimize the properties of silica‐based ceramic cores, the micro‐sized mullite content should not exceed 4.6 wt%.

Effects of flake-shape and content of nano-mullite on mechanical properties and fracture process of corundum composite ceramics

ABSTRACT Coal gangue is used to prepare flake nano-mullite with a molten salt method. In order to increase the utilization value, corundum composite ceramics were prepared from the nanomullite and alumina. The effect of particle size of the raw material size and the content of mullite on mechanical properties of the corundum composite ceramics was studied. It is found that the mullite with appropriate sizes can be filled in between the corundum grains, thus increasing the density of the samples. The mechanical properties were enhanced due to the variation in the crack propagation mode. The optimized sample exhibited flexural strength and fracture toughness of 263.7 MPa and 5.0 MPa·m1/2, respectively. Griffith fracture theory analysis results indicated that the critical crack size reached 173.9 μm and the fracture energy was 127.6 J/m2. Coal gangue has realized deep resource utilization, and the mechanical properties of composite ceramics are higher than alumina ceramics prepared under the same conditions. Flake nanomullite contributes to mechanical properties.

Development of high strength, porous mullite ceramic hollow fiber membrane for treatment of oily wastewater

Ceramic hollow fiber membranes (CHFMs) are known for their excellent characteristics including high surface area, compact design, and good chemical, thermal, and mechanical stabilities. Despite these interesting attributes, CHFMs are also prone to certain limitations, such as brittleness and high cost that hinder them from being commercialized. To mitigate this drawback, we have developed a high strength, porous ceramic hollow fiber membrane, derived from mullite–kaolinite powder, for efficient oil–wastewater separation. The superhydrophilic, low-cost mullite-based (CHFM) was successfully fabricated through combined phase inversion and sintering techniques. Prior to the fabrication, the as-received mullite–kaolinite was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analyses. Subsequently, operational parameters such as the effect of mullite content, sintering temperature, and air gap were optimized during the fabrication of mullite ceramic hollow fiber membrane. The resulting membranes were systematically characterized and evaluated in terms of morphology, porosity, mechanical strength, water flux, and oil–water separation. Increasing the mullite content, air gap, and sintering temperature enhanced the formation of microvoid structure. It is interesting to note that the mechanical strength of 86 MPa was obtained for the membrane containing 60 wt % of mullite sintered at 1450 °C and an air gap of 5 cm. The membrane induced a stable permeate water flux and oil rejection of mullite CHFM of 182 L/m2∙h and 97.1%, respectively. As compared to kaolin ceramic counterparts, this porous mullite ceramic hollow fiber membrane can be used in various water treatment applications, including for the separation of oily wastewater due to its mechanical strength and water flux.

Development and Properties of New Mullite Based Refractory Grog.

The presented study is focused on optimization and characterization of a high-alumina refractory aggregate based on natural raw materials—kaolins, claystone, and mullite dust by-product (used to increase the alumina and mullite contents, respectively). In total, four individual formulas with the Al2O3 contents between 45 and 50 wt.% were designed; the samples were subsequently fired, both in a laboratory oven and an industrial tunnel furnace. The effects of repeated firing were examined during industrial pilot tests. Mineral and chemical compositions and microstructures, of both the raw materials and designed aggregates, were thoroughly investigated by the means of X-ray fluorescence spectroscopy, powder X-ray diffraction, and optical and scanning electron microscopies. Porosity, mineral composition, and mullite crystal-size development during the firing process were also studied. Based on the acquired results, the formula with the perspective to be used as a new mullite grog, featuring similar properties as the available commercial products, however, with reduced production expenses, was selected. The quality of grog determines to a large extent the properties of the final product. Hence, optimization of aggregates for specific refractories is of a great importance. The production of engineered aggregates provides the opportunity to utilize industrial by-products.

Effects of Wheat Straw and Ashing Temperature on the Ash Fusion Characteristics of Food Waste

The disposal of food waste (FW) has brought severe challenges to the environment and society, the application of gasification technology provides new ideals for its resource utilization, and the effective slagging is one of the key points for this technology. This study mainly focuses on the ash fusion characteristics of FW under different temperature and wheat straw (WS) addition conditions, and analyses of XRF, XRD and SEM were performed to characterize the properties of the ashes. Results show that the ash fusion temperatures (AFTs) of FW were higher than that of WS, and both increased with the temperature due to the volatilization of alkali metals and the formation of high melting points substance such as quartz and mullite. The AFTs of FW decrease by about 23 °C with the blending of 10% WS at 800 °C, and it decreases non-linearly with increasing WS ratio, which mainly originated from the interaction between the ashes of FW and WS. Although the increase of mullite content makes the AFTs of WS50 higher than the calculated value, the increase of low melting point substances such as anorthite and the existence of leucite in WS50 resulting in its lower AFTs than that of FW.

Influences of Al metal and Al–Si alloys on in-situ synthesis of SiC nanowhiskers in porous Al2O3–SiC composites obtained by carbothermal reduction

SiC nanowhiskers are good reinforcing phases for enhancing the strength and thermal shock resistance of porous Al2O3–SiC composites. In this work, Al metal and Al–Si alloys were used as reducing agents to assist the in-situ synthesis of SiC nanowhiskers in the porous Al2O3–SiC composites prepared by carbothermal reduction method. The influences of Al metal and Al–Si alloys on the phase composition, microstructure, porosity and strength of the porous Al2O3–SiC composites were studied by XRD, SEM, TEM, etc. The results indicate that the use of Al metal and Al–Si alloys effectively promoted the carbothermal reduction and decreased the synthesis temperature of β-SiC phase from the original 1500 °C–1400 °C. SiC nanowhiskers were in-situ synthesized at a relatively low temperature of 1500 °C with the use of Al metal and Al–Si alloys. Al metal and Al–Si alloys effectively enhanced the strength of the porous composites by reducing the amount of pores and increasing the yield of SiC nanowhiskers. The samples that were added with Al–20Si alloy obtained the highest β-SiC yield of 23.2% and the highest flexural strength of 5 MPa. The thermal shock resistance of the porous composites was effectively enhanced by the in-situ synthesis of SiC nanowhiskers. The oxidation of SiC nanowhiskers during the thermal shock tests (room temperature to 1100 °C) could improve the flexural strength of the porous composites to 6.3 MPa by densifying the microstructure and increasing mullite content.

Influence of heating temperatures on structure and microstructure of chamotte–carbon composites

The reaction between chamotte and active carbon at high temperature and low oxygen partial pressure conditions has been investigated. Both components react at temperatures above 1400°C where cristobalite is reduced by the carbon while increases the mullite content. At 1600°C mullite tends to disappear due to the reduction reaction leading to the formation of alumina. The reaction between chamotte and active carbon in these conditions produces the reduction of silica and mullite. This process increases with the reaction time although not all the active carbon is consumed. The graphite nanodomain size of the active carbon tends to decrease with respect to the original size with both the temperature and the reaction time. The microstructures of the obtained materials present a glassy phase due to the inherent presence of impurities in chamotte, and where small particles, pores and mullite needles are also observed. The presence of this glassy phase becomes more pronounced with the treating temperature while solid particles and pores tend to disappear, moreover, the formation of the glassy phase occurs in a less extent due to the higher concentration of active carbon. The presence of the liquid glassy phase also favours the formation of the long-needle like mullite crystals.

Influence of Li2O Addition on the Performance of Vitrified Bond and Vitrified Diamond Composites

In order to develop high-performance diamond wheels, the vitrified bond with different contents of Li2O addition and corresponding diamond composites were prepared. The experimental results show that the addition of a small content of Li2O leads the formation of the mullite phase in vitrified bond. When the Li2O content is 3wt%, the mullite content in the vitrified bond reaches the maximum. Whereas, the vitrified bond turns into a pure glass phase when the Li2O content further increases to 5wt%. The softening temperature of vitrified bond, wetting angle between the vitrified bond and the diamond film decrease with the increasing of the Li2O content. The softening point of the vitrified bond with 5wt% Li2O is 537 °C and the contact angle is 32°, which are 44 °C and 44° lower than those of the sample without Li2O. The CTE (coefficient of thermal expansion), the flexural strength and hardness of the diamond composite sample first increase and then decrease with the increasing of the Li2O content. When the Li2O addition is 3wt%, the flexural strength and hardness of the composites reaches the maximum values of 93 MPa and 98 HRB, respectively, which are 43.1% and 12.6% higher than those of the sample without Li2O.