热中子透射法测陶料水分

报道了一种利用热中子透射计取样测量陶料水分的新方法。理论计算了江苏宜兴白泥的水分响应。实验标定了江苏宜兴白泥,湖南界牌马迹泥和山西紫木节土,标定曲线均符合透射率倒数的对数值与样品水分间的线性规律。测量水分的精度分别为±0.40wt％、±0.42wt％和±0.65wt％。

带密度修正的热中子透射计测陶料水分的研究

采用带密度修正的热中子透射计测陶料水分.因热中子透射率T_(n)和γ射线透射率T_(γ)均为样品水分百分含量P和质量W的函数,因而通过实验标定确定关系式P(T_n,T_γ)和W(T_n,T_γ).通过对陶料样品的实际考核,在实用范围内,质量测量误差 0.65g,水分测量误差0.43%(m/m),能满足现场使用要求.

陶粒焙烧窑机械总体设计

对陶粒焙烧窑机械总体设计中的参数、布置进行了介绍,详细阐述了设计步骤及相关问题。

谈陶粒砼墙体裂缝产生的原因及防治措施

针对陶料砼墙体裂缝产生的原因及防治措施。

粘土陶粒混凝土小砌块砌体抗压强度的试验与分析

1.概述 粘土陶粒混凝土小型空心砌块是采用粘土陶粒为粗骨料,普通水泥为胶凝材料加入适量水、外加剂,搅拌均匀经加压振动、成型、养护等工艺制成的一种新型轻质墙体材料。以陶粒为集料的陶粒混凝土已被广泛应用于墙体、楼板。

提高坭兴陶炼泥水平,做更好坭兴陶品质

本文讲述构成坭兴陶的主要化学成分,陶土原料中各类化学成分对坭兴品质的影响作用,坭兴陶泥料炼制过程中需要注意各种事项,着重解决的问题,通过不断实践检验,积累更多的经验,炼制出更好的泥料,让坭兴陶的品质表现更佳。

大冶地区瓷土粉磨特性研究

瓷土矿是花岗斑岩或流纹岩等岩石的风化产物,有些还呈较硬的岩石状。它能否直接球磨,球磨后的颗粒分布如何?颗粒度对泥浆的流动性影响如何?针对以上问题我门对大冶地区前山和金山瓷土进行了研究,同时对宜都江家湾的紫木节粘土作了测试,得出了瓷土和紫木节土各自不同的粉磨特性。

Evolution of microstructure and mechanical properties in multi-layer 316L-TiC composite fabricated by selective laser melting additive manufacturing

In this study,the microstructure and mechanical properties of a multi-layered 316L-TiC composite material produced by selective laser melting(SLM)additive manufacturing process are investigated.Three different layers,consisting of 316L stainless steel,316L-5 wt%TiC and 316L-10 wt%TiC,were additively manufactured.The microstructure of these layers was characterized by optical microscopy(OM)and scanning electron microscopy(SEM).X-ray diffraction(XRD)was used for phase analysis,and the mechanical properties were evaluated by tensile and nanoindentation tests.The microstructural observations show epitaxial grain growth within the composite layers,with the elongated grains growing predominantly in the build direction.XRD analysis confirms the successful incorporation of the TiC particles into the 316L matrix,with no unwanted phases present.Nanoindentation results indicate a significant increase in the hardness and modulus of elasticity of the composite layers compared to pure 316L stainless steel,suggesting improved mechanical properties.Tensile tests show remarkable strength values for the 316L-TiC composite samples,which can be attributed to the embedded TiC particles.These results highlight the potential of SLM in the production of multi-layer metal-ceramic composites for applications that require high strength and ductility of metallic components in addition to the exceptional hardness of the ceramic particles.

Microstructure and ablation behavior of Zr-based ultra-high-temperature gradient composites

To obtain high-performance Zr-based ultra-high-temperature composites,Zr-based ultra-high-temperature gradient composites were prepared by changing the laying method of the infiltrant via reactive melt infiltration.The effects of different infiltrant laying methods on the microstructure and ablative properties of Zr-based ultrahigh-temperature gradient composites were investigated.The results showed that the gradient structure of the Zr-based ultrahigh-temperature gradient composites differed when the composition ratio of the infiltrant was changed.When the thicknesses of the Zr/Mo/Si layers were 6/4/12 mm and 8/2/12 mm,the SiMoZrC solid solution content in the samples increased and decreased along the infiltration direction,respectively.The gradient samples were ablated in an oxyacetylene flame at 3000°C for 40 s.The ablation resistance of the sample was the highest when the infiltrant was a powder and the thickness of the Zr/Mo/Si layer was 6/4/12 mm.

Effects of alcohol additives on pore structure and morphology of freeze-cast ceramics

The porous alumina ceramics with lamellar structure were fabricated successfully by freeze casting. The viscosities of alumina slurries, pore structures, porosities and mechanical properties of the sintered ceramics were investigated by introducing both types of alcohols as water solidification modifier into the initial slurries, such as ethanol and 1-propanol. With the addition of ethanol or 1-propanol, the viscosities of slurries increased and porosities of sintered ceramics decreased. The compressive strengths of the sintered porous alumina ceramics were improved due to a good connectivity between lamellae with the addition of both types of alcohols. The lowest porosities of 68.52% and 73.72% and highest compressive strengths of 18.2 MPa and 15.0 MPa were obtained by the addition of 30% ethanol in mass fraction and 1-propanol, respectively.

EFFECT OF FIBER FAILURE ON QUASI-STATIC UNLOADING/RELOADING HYSTERESIS LOOPS OF CERAMIC MATRIX COMPOSITES

The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the global load sharing criterion.The axial stress distribution of intact fibers upon unloading and reloading is determined based on the mechanisms of fiber sliding relative to matrix in the interface debonded region.The interface debonded length,unloading interface counter slip length,and reloading interface new slip length are obtained by the fracture mechanics approach.The hysteresis loops corresponding to different stresses considering fiber failure are compared with the cases without considering fiber failure.The effects of fiber characteristic strength and fiber Weibull modulus on the fiber failure,the shape,and the area of the hysteresis loops are analyzed.The predicted quasi-static unloading/reloading hysteresis loops agree well with experimental data.

IMPROVING MATERIAL REMOVAL RATE OF BRITTLE CERAMICS THROUGH HONING INCIDENTAL TENSILE STRESSES

The stress intensity factors and stress conditions of machining cracks are analyzed by fracture mechanics on the basis of honing characteristics and of brittle ceramic mechanical behavior.Because the honing incidental tensile stresses effectively decrease the critical grinding stresses and increase the stress intensity factors of machining cracks,the honing process can be carried out easily.The results show that honing can be an efficient machining method for brittle materials.

RESEARCH ON MATRIX CRACK EVOLUTION OF CROSS-PLY CERAMIC MATRIX COMPOSITE

The matrix crack evolution of cross-ply ceramic matrix composites under uniaxial tensile loading is investigated using the energy balance method.Under tensile loading,the cross-ply ceramic matrix composites have five damage modes.The cracking mode 3 contains transverse cracking,matrix cracking and fiber/matrix interface debonding.The cracking mode 5 only contains matrix cracking and fiber/matrix interface debonding.The cracking stress of modes 3 and 5 appearing between existing transverse cracks is determined.And the multiple matrix crack evolution of mode 3 is determined.The effects of ply thickness,fiber volume fraction,interface shear stress and interface debonding energy on the cracking stress and matrix crack evolution are analyzed.Results indicate that the cracking mode 3 is more likely to appear between transverse cracks for the SiC/CAS material.

Electric characteristics of Nd_2O_3 doped BaTiO_3 ceramics

Nd2O3 doped BaTiO3ceramics（the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio）were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities through X-ray photoelectron spectrum （XPS）. The results showed that the dielectric characteristics of Nd2O3 doped BaTiO3 ceramics were improved by doping. When Nd2O3 content was 0.003 mol, the results were even better, the dielectric constant was increased, the dielectric loss was decreased, the Curie-temperature （Tc） was 110 ℃, and the frequency characteristic was also good. The resistivity of Nd2O3 doped BaTiO3 ceramics was lower than that of pure BaTiO3 ceramics, when Nd2O3 content was 0.001 mol,the resistivity was （2.364×）108 Ω·m, the smallest. The grain resistance of Nd2O3 doped BaTiO3 ceramics exhibited NTC effect, but the grain boundary resistance showed PTC effect, and the grain boundary resistance was larger than that of the grain resistance, so the PTC effect originated from the grain boundary. The analysis of the element binding energy through X-ray photoelectron spectrum were indicated that the quantivalence of Ba2+and Ti4+in Nd2O3 doped BaTiO3 ceramics was variable, and resulted in the improvement of the conductibility of BaTiO3 ceramics.

Effects of drying method on preparation of nanometer α-Al_2O_3

Ammonium aluminum carbonate hydroxide (AACH) precursor was synthesized by the precipitation reaction of aluminum sulfate and ammonium carbonate. Then the precursor was dealt with five drying methods including ordinary drying, alcohol exchange, vacuum freeze-drying, glycol distillation, n-butanol azeotropic distillation respectively and calcined at 1 200 ℃ for 2 h to get α-Al2O3. The effects of drying methods on preparation of nanometer α-Al2O3 were discussed, and the optimal drying method was confirmed. The structural properties of powders were characterized by XRD, SEM and BET measurements. The results show that vacuum freeze-drying, glycol distillation and n-butanol azeotropic distillation can prevent the powders from aggregating, and among them the n-butanol azeotropic distillation is the best method. The nanometer α-Al2O3 powder with non-aggregation can be manufactured using n-butanol azeotropic distillation and the average particle size is about 40 nm.

Preparation of high performance ceramic tiles using waste tile granules and ceramic polishing powder

This paper presents an innovative approach to reusing waste tile granules(TG) and ceramic polishing powder(PP) to produce high performance ceramic tiles.We studied formulations each with a TG mass fraction of 25.0% and a different PP mass fraction between 1.0% and 7.0%.The formulations included a small amount of borax additive of a mass fracton between 0.2% and 1.2%.The effects of these industrial by-products on compressive strength,water absorption and microstructure of the new ceramic tiles were investigated.The results indicate that the compressive strength decreases and water absorption increases when TG with a mass fraction of 25.0% are added.Improvement of the compressive strength may be achieved when TG(up to 25.0%) and PP(up to 2.0%) are both used at the same time.In particular,the compressive strength improvement can be maximized and water absorption reduced when a borax additive of up to 0.5% is used as a flux.Scanning electron microscopy reveals that a certain amount of fine PP granules and a high content of fluxing oxides from borax avail the formation of glassy phase that fills up the pores in the new ceramic tiles,resulting in a dense product with high compressive strength and low water absorption.

Sintering behavior and mechanical properties of sintered ceramics based on spodumene tailings

In this study,ceramics was prepared by slip casting(no pressure was used during shaping step)and atmospheric pressure sintering with low-melting point glass(LPG)powder as the binding material to facilitate the transformation of spodumene flotation tailings(SFTs)into ceramics at lower temperatures.The influence of sintering temperature and mass ratio of LPG on the mechanical properties(flexural strength and compressive strength)of ceramic materials was studied by orthogonal test.The results showed that when the mass ratio of LPG powder was higher than or equal to 20 wt%and the sintering temperature was higher than or equal to 550℃,mutual adhesion between the sample particles was realised and consequently the ceramic materials could be prepared with good mechanical properties(the maximum flexural strength=19.55 MPa,the maximum compressive strength=42.25 MPa,average porosity=24.52%,average apparent density=1.66 g/cm^(3),and average water absorption=14.79%).The sintered ceramics were characterized by XRF,XRD,optical microscopy analysis,SEM,TGA-DSC and FT-IR.The formation of liquid phase at high temperature may lead to the mutual bonding between particles,which might be the main reason for the improvement of mechanical properties of ceramic materials.Overall,SFTs were successfully sintered at low temperature to prepare ceramic materials with good mechanical properties,which are crucial for energy conservation and environmental preservation.