Effects of roughness parameters on slip resistance for different methods used to determine the coefficient of friction for ceramic floor tiles

This work attempts to evaluate the correlation between the roughness parameters and different standardized methodologies for determining the coefficient of friction of ceramic floor tiles. Eight different types of ceramic tiles were evaluated, and each one was characterized for their coefficient of friction/slip resistance in accordance with the standards NBR 13818, ANSI A137.1, and AS 4586. The surfaces were also characterized in relation to surface roughness by means of contact profilometry. The measured friction and roughness parameters were correlated by means of analysis of variance. The results showed a correlation tendency according to a third-degree equation for tests performed in wet conditions. The study results showed that the roughness parameters influence the coefficient of friction with a confidence level of 95%. Considering the safe values indicated for the respective standards for the evaluated methods, a Rz value of 25 μm ensures that a tested surface can be considered safe in a wet-condition test, regardless of the method used to determine the coefficient of friction.     

Non-isothermal modeling of drying kinetics of ceramic tiles

The present study has been undertaken to optimize the drying stage in ceramic tile manufacture. Tests were conducted to determine drying kinetics, establishing how air temperature and relative humidity influenced this process. Tests show that surface moisture content does not evolve as might be expected on the basis of the simple assumption that the surface dries immediately and reaches equilibrium moisture content. A non-isothermal model was proposed to model drying curves successfully. The influence of drying temperature, bulk density of the shaped material, and tile thickness on the drying process and the parameters of the model was obtained.     

陶瓷砖吸水率测试方法的探讨

就陶瓷砖国际标准测试方法ISO10545—3:1995与中国标准试验方法GB/T 3810.3—2006中采用真空法测试陶瓷砖吸水率存在的差异进行探讨,通过比对试验结果并将试验数据进行分析,提出了对现行中国陶瓷砖标准吸水率测试方法修改的建议。     

Perspective of the application of ash from the ceramic industry in the development of alkali-activated roof tiles

The construction industry is always in need of new technologies and products that improve technological characteristics. Alkali-activated materials appear as an alternative to reduce energy costs, improve technological properties and still present themselves as materials with the potential for incorporating industrial waste. The objective of this research was the development of roof tiles through the process of alkaline activation using ash from the kilns of burning of a red ceramic industry. After the process of processing the materials and their characterizations, prismatic specimens (115 × 30 × 20 mm) were made with the replacement of 0, 6.25, 12.5, 25 and 50% ash by metakaolin and subsequently separated into two groups, (i) subjected to curing at room temperature and (ii) subjected to curing at a temperature of 80 °C, in both cases with a curing time of 7, 14 and 28 days. After each curing period and group, the specimens were subjected to technological evaluation of water absorption, porosity, flexural strength and scanning electron microscopy. The results obtained demonstrate that the use of ash from ceramic waste, mainly replacing 12.5% of the metakaolin, promotes a reduction in water absorption and porosity, and an increase in flexural strength. The results obtained at 28 days in thermal curing are 44.05 MPa for 12.5% ash, much higher than the reference composition (16.02 MPa). The increase in strength happens due to the formation of tobermorite, due to the calcium present in the ash, and due to the formation of phases rich in potassium from the ash, such as kalsilite. Thus, it is concluded that the use of ash from ceramic waste is possible in the alkaline activation of roof tiles due to the occurrence of additional mechanisms of alkaline activation.     

Influence of firing temperature on the ceramic properties of clays from Campos dos Goytacazes, Brazil

The characteristics of two clays used for red ceramic production in Campos dos Goytacazes, southeast of Brazil, were investigated. Characterization was performed by X-ray diffraction, chemical analysis, as well as granulometric and plasticity measurements. Technological properties related to water absorption, linear shrinkage and flexural strength were obtained from specific tests. Samples were prepared by pressing clay bodies at 20 MPa, which were then fired at temperatures from 850 to 1200 °C. The results showed that both clays from three deposits are highly plastic due to the elevated percentage of kaolinitic clay minerals. The samples richer in clay minerals present higher linear shrinkage as well as a decrease in water absorption in comparison to the others. The effectiveness of these clays for red ceramic production has been discussed in terms of the Winkler diagram.     

A new eco-friendly mass formulation based on industrial mining residues for the manufacture of ceramic tiles

New eco-friendly mass formulations based on the scheelite and kaolin residues were developed to manufacture ceramic tiles. The start raw materials (scheelite residue, kaolin residue, feldspar and plastic clay) were characterized as to their chemical composition, main mineralogical phases, and particle size distribution. Three ceramic masses with 37 wt% of kaolin residues and different contents of the scheelite residues (2 wt%, 5 wt%, and 10 wt%) were formulated. The mass formulations were uniaxially pressed (19.6 MPa) to obtain samples with dimensions of 60 mm × 40 mm x 7 mm, which were dried at 110 °C/24 h, and sintered at different temperatures (1150 °C, 1200 °C, and 1250 °C). Dilatometric experiments measured thermal expansion coefficients. The results are in agreement with the literature, i.e., 6.0 μm/m°C^?1, 6.1 μm/m°C^?1 and 6.4 μm/m°C^?1 to samples with 2 wt%, 5 wt%, and 10 wt% of scheelite residues, respectively. The potential of the mass formulations studied was evaluated by linear shrinkage, water absorption, apparent density, apparent porosity, flexural strength, and mineralogical phase identification. The results were compared with the literature experimental data and International Technical Standards. It was concluded that the samples investigated have suitable properties for use as ceramic and porcelain tiles. Also, the pseudowollastonite and mullite phases were identified in the sample with the lowest concentration of scheelite residue. These phases are responsible for increasing flexural strength.     

国外陶瓷墙地砖工艺装备发展趋势

详细介绍了陶瓷墙地砖产品品种及生产工艺装备的发展趋势     

Characterization of clays used in the ceramic manufacturing industry by reflectance spectroscopy: An experiment in the São Simão ball-clay deposit, Brazil

The characterization of clays from the physical, chemical, and ceramic standpoint in pre-and-within mining stages is a necessary step. However, succinct mining planning, lack of industry-oriented standards and the usual bond to empirical discrimination of clays as regards their use, imply in mixing chemically and technologically different materials, with serious consequences to the mining and manufacturing process. Taking the alluvium-derived, ball-clay deposit of São Simão (SS) as a case study, this works aims to evaluate the potential of reflectance spectroscopy (RS) as a method to define types, purity and crystallinity of clays and to seek a possible relation between spectral characteristics of clays and their use in the ceramic industry. The SS deposit hosts three types of clays that were spectrally set apart based on RS. The technique indicated that the white clays comprise highly ordered kaolinite, mica, smectite and lepidocrosite (first finding in Brazilian alluviums). The brown clays are also rich in well-ordered kaolinite and contain abundant Fe-bearing minerals, as goethite, hematite and siderite (rarely found in alluviums). The gray clays are kaolinite-poor and are abundant in organic matter and smectites. Each of the clay classes typified in the SS deposit has a specific application in the fine ceramic industry, indicating the prominent potential of RS to characterize industrial materials.     

Sintering mechanism of high-intensity and low-density ceramic proppants prepared by recycling of waste ceramic sands

Waste ceramic sands were effectively used to prepare the high-intensity and low-density ceramic proppants, realising the recycling of the waste ceramic sands. The technology involved the pelletising in an intensive mixer, in which the waste ceramic sands and other starting materials were added, and followed by heat-treatment under different sintering conditions. The sintering temperature, holding time and heating rate were optimised by investigating the crystalline phase, microstructure, density and breakage ratio of the obtained proppants. The results showed that the proppants sintered at 1260°C for 2?h with a heating rate of 5°C?min^–1 under air atmosphere exhibited high crush resistance and low density, with the breakage ratio of 8.5% under 52?MPa closure pressure and bulk density of 1.65?g?cm^–3. The proppants prepared by bauxite, waste ceramic sands and sintering aids are promising candidates as high-intensity and low-density fracturing proppants in future applications.     

Technological characterization and ceramic application of gravel pit by-products from middle-course Jarama river deposits (central Spain)

This work, unlike previous others, deals with ceramic products obtained exclusively from gravel pit by-products. The residues are originated from the sand and gravel washing process of middle-course Jarama river Quaternary sediments, located in Madrid region, central Spain. These natural aggregates allow an intense exploitation, because of quality (well-rounded quartzite) and reserves (up to 700×10⁶ m³), generating considerable waste volumes.Thirty silty–clay by-products, collected from seven gravel pits, have been tested at a laboratory scale. The mineralogical composition of these materials is mainly represented by phyllosilicates (muscovite-illite, smectite, kaolinite and chlorite), quartz and feldspars.For the technological characterization, six representative mixtures (M1 to M6) were designed combining suitable mineralogy and grain-size distribution of the 30 raw samples. A wide range of values was measured on mixture powders, determining specific surface (13–76 m² g⁻¹, BET method), methylene blue index (5–20) and Atterberg limits (W_l: 43–90; W_p: 25–38).Ceramic characterization was performed on extruded bodies, testing drying sensitivity (Bigot curves and Ratzemberger test). Smectitic content influences directly the parameters measured on dried bodies. This influence can be controlled by increasing the silty component, and the ceramic properties measured on these mixtures (M3, M4 and M5) get better: hygroscopicity (less than 2%), drying shrinkage (4–7 cm m⁻¹), keeping the bending strength above 5 MPa.Three maximum firing temperatures were studied: 850, 950 and 1050 °C. On mixtures fired at 950 °C, firing shrinkage is less than 4 cm m⁻¹, bending strength may reach 69 MPa and water absorption range from 23% to 0.5%. Efflorescence susceptibility is faint, and colour is red for all the samples, getting darker for increasing temperature.The positive results obtained in this set of preliminary tests drive to envisage new research programs, focused on testing these by-products on a semi-industrial scale, assessing the effective possibilities of using them as ceramic raw materials.     

Ablation behavior of a network interlacing ZrC-VC ceramic coating prepared by a pioneering spillover permeation

A novel network interlacing ZrC-VC ceramic coating was prepared by a pioneering spillover permeation. With the increase of Zr content in the blind vias, the content of ZrC in the coating and the density of the coating all decrease. The density of the coating on C/C–ZrC–SiC substrate is obviously higher than that on C/C substrate. The linear ablation rate of the novel ceramic coated C/C–ZrC–SiC composites was ?0.06 μm/s with about 20 and 1.56 times reduction than C/C composites and C/C–ZrC–SiC composites respectively. The improved ablation resistance was attributed to a dense honeycomb ZrO₂ layer filled with liquid vanadium oxide in the ablation center and the improved thermal radiation.     

Structure and properties of ceramic fibers prepared from organosilicon polymers

This paper is a review of structure and properties of ceramic fibers derived from organosilicon polymers, with emphasis on the author's research. Ceramic fibers are prepared from organosilicon polymers by melt-spinning, cross-linking, and pyrolysis. Desirable polymeric precursors display the following properties: high char yield of desired composition, thermal stability at melt-spinning temperature, stable rheology, high purity and freedom from particulate impurities, and ability to undergo rapid cure (cross-linking). Ceramic fibers in the Si-C-O or Si-C-N-O systems display a rich nanostructure consisting of some or all of the following metastable phases: (1) an amorphous, continuous siliconoxycarbide or siliconoxycarbonitride phase; (2) dispersed carbon nanocrystallites; (3) dispersed -SiC or Si₃N₄ nanocrystallites; and (4) closed, globular nanopores. The crystalline phases increase in volume fraction and crystallite size as stoichiometry approaches the crystalline composition and as pyrolysis temperature increases. The Si-C-N-O fibers are amorphous. Pore size increases and total pore volume decreases with increasing pyrolysis temperature. Considerable variation in ceramic fiber composition can be achieved by varying cure conditions and pyrolysis atmosphere. Polycrystalline SiC fibers can be produced by pyrolysis above 1600°C. Fiber diameters range from 7 to 20 µm. Elastic moduli vary from 140 to >420 GPa (20 to >60 Msi) and are controlled by composition, nanostructure, and fiber density. Fiber densities range from 2.2 to >3.1 g/cm³. Tensile strengths range up to 5 GPa (700 ksi) and are Griffith flaw-controlled.This review is from the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

A study of the oxidation behavior of CrN and CrZrN ceramic thin films prepared in a magnetron sputtering system

CrN and CrZrN ceramic thin films were produced by a planar type reactive sputtering system on glass and stainless steel substrates. We investigated oxidation resistance of CrN and CrZrN ceramic thin films with different Zr contents. The structure of the films at different thermal-annealing temperatures was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The mechanical properties of the films at different thermal-annealing temperatures were measured by nano-indentation. The results of this study showed that the addition of few amount of Zr (0.4 at%), can improve thermal stability of CrZrN ceramic thin film and increase the oxidation temperature of the film from 600 °C to 800 °C. The relatively good oxidation resistance (800 °C) and high hardness of the film with the lowest Zr content, indicates that this film is a good candidate for high temperature applications.     

The influence of shaping and firing technology on ceramic properties of calcareous and non-calcareous illitic–chloritic clays

Two very different illitic–chloritic clays (calcareous and non-calcareous), both currently used in the Italian brickmaking industry, were used. Technological testing consisted in a simulation of the industrial processing performed at a laboratory scale. The pieces were obtained by three shaping techniques, pressing, extrusion and moulding, and fired at 1000 and 1100 °C, in fast and slow heating cycles. In each case their technological properties were studied. The microstructure and technological parameters of the ceramic pieces vary greatly, depending on the clay composition and the processing techniques. Pressing always produces pieces made from non-calcareous clay with the lowest drying and firing shrinkage, open porosity and water absorption. As it regards the calcareous clay, the lowest values of drying and firing shrinkage and water absorption are obtained by extrusion and moulding, respectively. The mechanical resistance, pore size distribution and critical pore diameter do not reflect clearly the influence of shaping techniques. Independently from the shaping technique adopted, all non-calcareous bodies show higher Maage's indexes than the calcareous ones. In any case, the Maage's durability factor is higher in extruded samples.     

Studies on polymeric conservation treatments of ceramic tiles with Paraloid B‐72 and two alkoxysilanes

The aim of this study was to evaluate the effect of different polymeric protections applied on ceramic tiles on their mechanical and water absorption properties. Three conservation products were used: the acrylic polymer Paraloid B‐72 and two alkoxysilane‐based formulations (tetraethoxysilane (TEOS) and IN2210, a polidimetilsiloxane‐based formulation). The coatings were applied onto handmade tiles manufactured according to a 18th century procedure. Different application procedures (immersion, brushing, and spraying) were tested. The protection effectiveness was assessed through capillary water absorption and four point bending tests. The mineralogical characterization of tiles was undertaken by XRD. The best protective properties of the tiles were achieved by immersion treatments with Paraloid B‐72 based on the protocols followed by the museums restoration departments. Nevertheless, the results of the present work show that the second immersion in Paraloid B‐72 solution, commonly made, can be eliminated, as it does not provide any significant increase in the hydrophobic or mechanical properties of the tiles. As a result, there are obvious economical benefits, as the coating process became less time‐consuming and more environmental friendly, as the amount of organic compounds is reduced. On the other hand, the use of small volumes of Paraloid B‐72 solution applied by brush, or IN2210 sprayed can provide good results, if the only purpose of the treatment is the increase of the hydrophobic properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fabrication of low cost,green silica based ceramic hollow fibre membrane prepared from waste rice husk for water filtration application

In order to develop low cost ceramic membranes and effectively utilize abundantly and dumped waste agriculture, fabrication of green silica based ceramic hollow fibre membranes from waste rice husk was evaluated. Rice husk was converted into amorphous and crystalline silica based rice husk ash (ARHA and CRHA) by burning process at 600?°C and 1000?°C, respectively. The properties of silica based rice husk ashes were studied by transmission electron microscopy (TEM), x-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), BET analysis, thermogravimetry and differential thermal analysis (TG/DTA) and x-ray fluorescence (XRF). Effect of silica content and sintering temperature towards membrane fabrication were investigated and characterized in term of morphological properties, mechanical strength, surface roughness, pore size distribution, porosity and pure water flux (PWF). The ceramic hollow fibre membrane (CHFM) prepared at 37.5?wt% CRHA content and sintered at 1200?°C achieved a good mechanical strength (71.2?MPa) and excellent porosity (50.2%). As a result, high PWF with value ~ 300?L/m² h and stable at 20?min was obtained. Due to the excellent pure water flux, the prepared ceramic membrane from waste rice husk hold promise for water treatment application.     

Synthesis and properties of novel alicyclic‐functionalized polyimides prepared from natural—(D)‐camphor

In this article, a new alicyclic‐functionalized diamine, 1,3‐bis(4‐aminophenoxymethylene)‐1,2,2‐trimethylclopentane (BAMT) was successfully synthesized starting from natural —(D)‐camphor through four reaction steps of oxidation to offer a dicaboxylic acid, reduction to offer a diol, nucleophilic substitution to give a dinitro compound and then reduction to give the final diamine. Two alicyclic‐containing polyimides were prepared by polycondensing BAMT with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 4,4′‐oxydiphthalicanhydride (ODPA), respectively. For the studies of the structure–property relationships of the polyimides, one aromatic polyimide of 4, 4′‐oxydianiline (ODA) polycondensed with ODPA was prepared in comparison. The alicyclic‐containinig polyimides PI (BPDA‐BAMT) and PI (ODPA‐BAMT) maintain good thermal properties with glass transition temperatures (T_g) of 257°C and 240°C, and temperatures at 5% weight loss (T₅) of 443°C and 436°C in nitrogen, respectively. The alicyclic polyimides exhibit tensile strengths of 91.9–133 MPa, Young's moduli of 2.75—3.24 GPa, and elongations at break of 5.6–18%. Compared with the aromatic polyimide PI (ODPA‐ODA), PI (ODPA‐BAMT) shows improved transparency with the UV‐Vis transmittance at 500 nm over 80%. In addition, PI (ODPA‐BAMT) displays better solubility than PI (ODPA‐ODA), which has been confirmed by the bigger d‐spacing value of PI (ODPA‐BAMT) than that of PI (ODPA‐ODA) calculated from the Wide‐angle X‐ray Diffraction spectra. This study indicates that the renewable forestry compound, such as natural —(D)‐camphor, could be a good origin for the structural designing and preparation of alicyclic‐containing polyimides with outstanding combined features suitable for advanced microelectronic and optoelectronic applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fabrication of β‐tricalcium phosphate composite ceramic scaffolds based on spheres prepared by extrusion‐spheronization

In this study, β‐tricalcium phosphate/phosphate‐based glass (β‐TCP/PG) composite spheres were prepared by an extrusion‐spheronization method featuring high production and fine control of sphere size. Subsequently, fully interconnected β‐TCP composite ceramic sphere‐based (TCCS) scaffolds were fabricated by sintering the randomly packed β‐TCP/PG composite spheres. The results manifested that at least 20% microcrystalline cellulose (MCC) was required to obtain β‐TCP/PG composite spheres in good spherical shape. The prepared TCCS scaffolds showed hierarchical pore architecture, which consisted of interconnected macropores among the spheres, a hollow core in the sphere, plentiful medium‐sized pores in the sphere shell and micropores among the grains. The pore architecture and mechanical strength of the TCCS scaffolds could be tailored by adjusting the sintering temperature, sphere size, and amounts of PG and MCC in the β‐TCP/PG composite spheres. This work is believed to open up new paths for the design and fabrication of interconnected bioceramic scaffolds for application in bone regeneration.     

Passivation of metal alloys using sol–gel-derived materials — a review

The sol–gel method is being investigated as an environmentally compliant alternative for chromate-based conversion coatings currently in use. An overview of recent advances in the use of sol–gel derived coatings for improved corrosion resistance of aluminum and steel metal surfaces is given.     

Removal of 3—(3,4—dichlorophenyl)—1, 1 dimethylurea from aqueous solution by natural and activated bentonite

The adsorption of 3-(3,4-dichlorophenyl)-1,1 dimethylurea (diuron) on bentonite desiccated at 110°C untreated, and acid treated with H₂SO₄ solutions over a concentration range between 0.25 M and 5.00 M, from aqueous solution at 30°C has been studied. In addition, adsorption of diuron on combined acid/heat treated samples (0.50 M and 2.50 M H₂SO₄/200°C and 400°C) has also been studied. The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (K) of the samples; K values range from 0.92 μg g^?1 for the untreated bentonite up to 974.42 μg g^?1 for the 0.50 M H₂SO₄/400°C acid/heat treated bentonite. The removal efficiency (R) has also been calculated; R values ranging from 2.02% for the untreated bentonite up to 97.17% for the 0.50 M H₂SO₄/400°C acid/heat treated bentonite. The adsorption experiments show that bentonite heat treatment is more effective than bentonite acid treatment in relation to adsorption of diuron.