Shaped Insulating Refractory Products —— Determination of Bulk Density and True Porosity

1 Scope This standard specifies a method for the determination of the bulk density and t rue porosity of shaped insulating refractory products.1 Scope This standard specifies a method for the determi- nation of the bulk density and true porosity of shaped…     

Refractory Products-Determination of Abrasion Resistance at Ambient Temperature

1 Scope This standard specifies the terms and definitions,theory,apparatus,specimens,test procedures,calculation results,apparatus check and test reports,etc.of abrasion resistance at ambient temperature of refractory products. This standard is applicable to determine the abrasion resistance at ambient temperature of dense refractory products used in erosion and corrosion conditions.     

Magnesia Bricks and Magnesia Alumina Bricks

正GB/T2275-2007 1Scope This standard specifies the classification,technical requirements,test methods,quality appraisal procedures,marking,packing,transportation,storage and quality certificate of magnesia bricks and magnesia alumina bricks.This standard is applicable to burned magnesia bricks and magnesia alumina bricks for industries of     

Shaped Refractory Products Rules of Acceptance,Sampling and Inspection

正1 Scope This standard specifies the terms,definitions,symbols,preparation,implementation,decision rules of products quality and test reports of acceptance sampling and inspection of shaped refractory products.This standard applies to acceptance sampling and inspection of normal shaped refractory products.For abnormal(extra-heavy or extra-light in unit)and valuable shaped refractory products,the standard also applies.     

Shaoed Refractory Products-Rules of Acceptance,Sampling and Inspection GB/T 10325

1 Scope This standard specifies the terms, definitions, symbols, preparation, implementation, decision rules of products quality and test reports of acceptance sampiing and inspection of shaped refractory products. This standard applies to acceptance sampling and inspection of normal shaped refractory products. For abnormal （extra-heavy or extra-light in unit） and valuable shaped refractory products, the standard also applies.     

Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials——Gravimetric method for determination of loss on ignition

GB/T 5069.1-1985 1 Scope This standard specifies the gravimetric method for determination of loss on ignition. This standard is used for the determination of loss on ignition of magnesia and magnesia-alumina refractory materials. Determination range: ≥…     

Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials ——Flame atomic absorption spectrometric method for determination of calcium oxide content

GB/T 5069.10-2001 1 Scope This standard specifies the determination of calcium oxide content by flame atomic absorption spectrometric method. This standard applies to the determination of calcium oxide content in magnesia and magnesia-alumina refrac…     

Chemical Analysis Method for Carbon Bearing Refractory Products——Determination of Magnesium Oxide Content by CyDTA Volumetric Method

GB/T 13246-91 1 Scope This standard specifies the method summary, reagents, apparatus, sampling, procedure, test results calculation and permissible tolerance of the determination of magnesium oxide by CyDTA volumetric method.This standard applies to the determination of magnesium oxide content in between 60% and 85% in magnesia-carbon bricks     

Magnesia Carbon Brick YB 4074-91

1 Scope This standard specifies the classification, technical requirements, test method, inspection rules, marking, packing, transportation and storage of magnesia carbon brick.     

Chemical Analysis Method for Magnesia and Magnesia-Alumina Refractories——Gravimetric-Molybdenum Blue Photometric Method for Determination of Silicon Dioxide Content

GB/T 5069.3-2001 1 Scope This standard specifies the gravimetric-molybdenum blue photometric method for determination of silicon dioyide content.This standard is used for the determination of silicon dioxide content of magnesia and magnesia-alumina refractory materials. Determination range: >5.00%.     

Porosity of refractories

Conclusions To improve the quality control of refractory products we recommend that a study be made of the economic advantages of incorporating the term total porosity in standards and technical specifications alongside apparent porosity, and that the channel porosity and dimensions of channel pores for certain Soviet fireclay refractory products be determined.Translated from Ogneupory, No. 8, pp. 50–53, August, 1967.     

Porosity measurement of fragile agglomerates

Agglomeration processes in the food and pharmaceutical industries frequently produce porous, brittle agglomerates intended for redispersion in liquids (a.k.a. “instant powders”). Typical products have a porosity ranging from =0.4 to =0.8 and a particle size between 0.2 and 2 mm. The agglomerate porosity is an important product property, as it has a major influence on the wetting behaviour. Due to their high porosity and comparatively weak internal bondings, instant agglomerates are fragile.

Compared to the wide range of currently available particle sizing methods, few porosity-measuring methods exist, most of which are not applicable to instant agglomerates. For controlling the porosity of instant agglomerates produced in our laboratory, we used individual particle weighing and sizing. A balance with 1 μg of precision allowed reliable weighing of individual agglomerates as small as 300 μm diameter. The volume of the particles was determined using a long-distance microscope with CCD camera attached to a computer running public domain image analysis software.

Porosity measurements of agglomerated skim and whole milk powder, agglomerated pectin, agglomerated flour/maltodextrin mixture, and agglomerated rice starch/maltodextrin mixtures were carried out. The results of our measurements show, for the majority of the samples, an approximately constant porosity over a wide particle size range, with a tendency towards lower porosity for smaller particles.     

Porosity control of porous silicon carbide ceramics

Porous SiC ceramics were fabricated by the carbothermal reduction of polysiloxane-derived SiOC containing polymer microbeads followed by sintering. The effect of the SiC powder:polysiloxane-derived SiC (SiC:PDSiC) ratio on the porosity and flexural strength of the porous SiC ceramics were investigated. The porosity generally increased with decreasing SiC:PDSiC ratio when sintered at the same temperature. It was possible to control the porosity of porous SiC ceramics within a range of 32–64% by adjusting the sintering temperature and SiC:PDSiC ratio while keeping the sacrificial template content to 50 vol%.The flexural strengths generally decreased with increasing porosity at the same SiC:PDSiC ratio. However, a SiC:PDSiC ratio of 9:1 and a sintering temperature of 1750 °C resulted in excellent strength of 57 MPa at 50% porosity. Judicious selection of the sintering temperature and SiC:PDSiC ratio is an efficient way of controlling the porosity and strength of porous SiC ceramics.     

高孔隙多孔陶瓷材料的制备工艺

从分析网状结构多孔陶瓷材料的孔隙形成机理着手，描述了高孔隙网状结构陶瓷材料的制备工艺。其中主要包括高孔隙纤维网状结构陶瓷材料的制备工艺及高孔隙泡沫陶瓷材料的制备工艺。     

静电喷雾法制备聚醚砜多孔微球孔隙率的控制研究

采用静电喷雾法制备了聚醚砜(PES)多孔微球,通过加入亲水性聚合物聚乙烯醇(PEG)和聚乙二醇(PVA)来调控PES多孔微球的孔隙率,利用扫描电子显微镜和热失重法分析仪表征了PES多孔微球的形貌和孔隙率。结果表明,加入亲水性聚合物PEG和PVA均能显著提高PES多孔微球的孔隙率,且随着其添加量的增多,孔隙率呈先增大后减小的趋势;PVA对PES多孔微球孔隙率的调控效果优于PEG,当PVA添加量为3%(质量分数,下同)时,PES多孔微球孔隙率达到最高值91.35%。     

Porosity study on free mineral addition cement paste

A study of the hydration process and the porosity evolution in a cement paste is presented. The analysis of porosity was made in samples with water to cement ratios (w/c) of 0.24, 0.40 and 0.60 at age of 3, 7, 28 and 365 days, respectively. Information on the evolution of total porosity and on the strength of the paste were obtained using positron annihilation lifetime spectroscopy (PALS), scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical tests (compression and flexion) and water absorption techniques. Specifically, positron lifetime technique allowed us to analyze the evolution of gel and capillary porosity during the hydration process. Using a simple function proposed, reasonable fits to the experimental data of the porosity evolution as a function of the compression strength were obtained.     

Porosity and mechanical properties of cement mortar

The effect of volume fraction porosity on the mechanical properties of cement mortar is studied. It is shown that both the Young's modulus and fracture toughness decrease with porosity. Although the flexural strength also decreases with porosity the linear relationship is largely fortuitous. Maximum size pores do not act as critical flaws in controlling flexural strength. The critical crack size is several times larger than the maximum pore size due to stable crack growth according to the crack growth resistance curve concept applied to cement mortar.     

Study of Porosity in Corroded Refractories

In this work, computer image analysis was used in order to characterize the complex porosity found in ceramic refractory materials. The porosities of SiC and Al₂O₃ refractory bricks before and after slagging tests have been examined by both mercury porosimetry and image analysis techniques; the results obtained by these two methods were compared and their differences discussed. Mercury porosimetry underestimated the volume fraction of pores larger than 100 μm, which contributed significantly to the total pore volume of analyzed materials. In contrast, image analysis did not reveal finer porosity, the contribution of which was, however, less important, Image analysis appeared to have the advantage of quantification of local heterogeneities of porosity, and the capabilities of this technique to quantify the variations in the volume of pores adjacent to reaction zones are documented and supported by microscopic observations.     

Research for Optimizing Porosity of Porous Thermal-insulating Materials

With the energy crisis and ecological environment deterioration, porous thermal-insulating materials become an advanced research hotspot,and the influence of pore distribution cannot be ignored. The mathematical model is established basing on the heat transfer theory,regarding the minimum heat flux density as the objective function,the constant total porosity as a constraint condition,using the BFGS method to optimize the pore distribution. The results show that when the heat flux is the minimum,in the case of the fixed total porosity,the high temperature zone has high porosity,the low temperature zone has low porosity; the maximal fluctuating amplitude of porosity between the adjacent discrete points has great impact on the thermal insulating performance,the greater the fluctuating amplitude,the better the thermal insulating ability. After calculating the temperature field of the corresponding physical model, it can be found that the temperature gradient is non-uniform,the temperature gradient of the high temperature zone is steep,and that of the low temperature zone is gentle.These results have guiding significance for preparation of porous thermal-insulating materials.     

Porosity in combustion synthesized titanium carbides

Stoichiometric and non-stoichiometric titanium carbides were obtained by combustion synthesis. Ignition of compacts of titanium containing either graphitic or activated carbons resulted in titanium carbides. Adsorption-desorption isotherms of carbons and combustion synthesized carbides were constructed and compared to determine the pore structural changes resulting from the synthesis. Original porosity of the carbon was lost after combustion synthesis, and the loss of porosity due to combustion synthesis is attributed to the reaction between liquid titanium and carbon.