Recycling of Glass Fibers from Fiberglass Polyester Waste Composite for the Manufacture of Glass-Ceramic Materials

This work presents the feasibility of reusing a glass fiber resulting from the thermolysis and gasification of waste composites to obtain glass-ceramic tiles. Polyester fiberglass (PFG) waste was treated at 550℃ for 3 h in a 9.6 dm3 thermolytic reactor. This process yielded an oil (≈24 wt%), a gas (≈8 wt%) and a solid residue (≈68 wt%). After the polymer has been removed, the solid residue is heated in air to oxidize residual char and remove surface contamination. The cleaning fibers were converted into glass-ceramic tile. A mixture consisting of 95 wt% of this solid residue and 5% Na2O was melted at 1450℃ to obtain a glass frit. Powder glass samples (<63 μm) was then sintered and crystallized at 1013℃, leading to the formation of wollastonite-plagioclase glass-ceramic materials for architectural applications. Thermal stability and crystallization mechanism have been studied by Differential Thermal Analysis. Mineralogy analyses of the glass-ceramic materials were carried out using X-ray Diffraction.

Mechanical and Microstructural Analysis of Waste Ceramic Optimal Concrete Reinforced by Hybrid Fibers Materials: A Comprehensive Study

Combining different types of fibers inside a concrete mixture was revealed to improve the strength properties of cementitious matrices by monitoring crack initiation and propagation.The contribution of hybrid fibers needs to be thoroughly investigated,considering various parameters such as fibers type and content.The present study aims to carry out some mechanical and microstructural characteristics of Waste Ceramic Optimal Concrete(WOC)reinforced by hybrid fibers.Reinforcement materials consist of three dif­ferent fiber types:hook-ended steel fiber(HK),crimped steel fiber(CR)and polyvinyl alcohol(PVA)fibers and the effect of their addition on the waste ceramic composites’mechanical behaviour.Furthermore,a micro­structural analysis was carried out to understand the waste ceramic matrix composition and its bonding to hybrid fibers.Results showed that the ad­dition of hybrid fibers improved the strength characteristics of the ceramic waste composites.For instance,the existence of PVA-CR increased the tensile and flexural strength of the waste ceramic composite by 85.44%and 70.37%,respectively,with respect to the control sample(WOC).As well as hybrid fiber exhibits improved morphological properties as a result of in­creased pore filling with dense and compact structure,as well as increased C-H crystals and denser structure in pastes as a result of the incorporation of hybrid fibers into the concrete mix.The present experimental research shows the choice of using steel fiber with PVA as a reinforcement material.The idea of adding hybrid fiber is to prepare the economic,environmental,and technological concrete.Moreover,it offers a possibility for improving concrete’s durability,which is vital.Finally,it was concluded that steel fiber is more durable,and stiffer and provides adequate first crack strength and ultimate strength.In contrast,the PVA fiber is relatively flexible and improves the post-crack zone’s toughness and strain capacity.

Preparation of Crack-free 3Y-TZP/Al_2O_3 Composite Ceramic Fiber by Electrolysis-sol-gel Method

Polycrystalline 3Y-TZP/Al2O3 tetragonal zirconia fiber was obtained by the pyrolysis of gel fibers using zirconium oxychloride octahydrate（ZOC） as the raw material. The spinnable zirconia sol was prepared by electrolyzing the zirco-nium oxychloride octahydrate（ZOC） solution in the presence of acetic acid and sugar（ sucrose, glucrose or fructose） , in which the molar ratios of CH3 COOH/ZOC and sugar/ZOC were 1.0-4.0 and 0.2-0.4, respectively. The pre- pared tetragonal zireonia fibers sintered at different temperatures showed smooth and crack-free surfaces with diame, ters of 5-10 μm. The addition of Al2O3 enhanced the sintering process and prevented the crystals from growing. Thermogravimetric analysis（TG）, X-ray diffraction （ XRD ）, Fourier transform infrared spectroscopy（FTIR）, and scanning electron microscope（SEM） techniques were used to characterize the prepared fibers.

Polydimethylsiloxane (PDMS) Composite Membrane Fabricated on the Inner Surface of a Ceramic Hollow Fiber: From Single-Channel to Multi-Channel

The fabrication of a separation layer on the inner surface of a hollow fiber (HF) substrate to form an HF composite membrane offers exciting opportunities for industrial applications, although challenges remain. This work reports on the fabrication of a polydimethylsiloxane (PDMS) composite membrane on the inner surface of a single-channel or multi-channel ceramic HF via a proposed coating/crossflow approach. The nanostructures and transport properties of the PDMS HF composite membranes were optimized by controlling the polymer concentration and coating time. The morphology, surface chemistry, interfacial adhesion, and separation performance of the membranes were characterized by fieldemission scanning electron microscope (FE-SEM), attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, the nano-indentation/scratch technique, and pervaporation (PV) recovery of bio-butanol, respectively. The formation mechanism for the deposition of the PDMS layer onto the inner surface of the ceramic HF was studied in detail. The optimized inner surface of the PDMS/ceramic HF composite membranes with a thin and defect-free separation layer exhibited a high flux of ~1800 gm-2h-1 and an excellent separation factor of 35–38 for 1 wt% n-butanol/water mixtures at 60
C. The facile coating/cross-flow methodology proposed here shows great potential for fabricating inner-surface polymer-coated HFs that have broad applications including membranes, adsorbents, composite materials, and more.

Effect of aluminum silicate fiber modification on crack-resistance of a ceramic mould

To improve the crack-resistance of the mould for silica sol bonded quartz based ceramic mould casting,aluminum silicate fibers with the diameter ranging from 5 μm to 25 μm and the length about 1 mm were dispersed in the ceramic mould.The effect of the aluminum silicate fibers on the tensile strength,shrinkage rate and the cracking trend of the ceramic mould were investigated.In the ceramic slurry,quartz sand was applied as ceramic aggregate,silica sol containing 30% silicon dioxide as bonder,and the weight ratio of quartz sand to silica sol was 2.69;the dispersed fibers changed from 0 to 0.24vol.%.The mould samples were formed after the slurry was poured and gelled at room temperature,and then sintered at different temperatures ranging from 100 to 800 ℃ to measure the tensile strength and shrinkage rate.The results show that,with the aluminum silicate fiber addition increasing from 0 to 0.24vol.%,the tensile strength increases linearly from 0.175 MPa to 0.236 MPa,and the shrinkage rate decreases linearly from 1.75% to 1.68% for the ceramic mould sintered at 400 ℃,from 1.37% to 1.31% for the ceramic mould at room temperature.As the sintering temperature was raised from 100 ℃ to 800 ℃,the tensile strength increases,and the shrinkage rate decreases at all temperatures,compared with those without fiber dispersion,but their variation patterns remain the same.Furthermore,the cracking trend of the mould and its decreasing proportion were defined and analyzed quantitatively considering both effects of the fiber dispersion on the strength and shrinkage.The cracking trend appears to decrease linearly with increasing fiber content and to reach the maximum reduction of 28.8% when 0.24vol.% fiber was dispersed.Therefore,the investigation proposes a new method to improve the crack-resistance of the ceramic mould,i.e.,inorganic fiber dispersion into the ceramic mould.

Properties of Ceramic Fiber and Ceramic Shot in Wet-laid Processes

The paper deals with the different sinking properties of ceramic fiber and the ceramic shot in wetlaid nonwoven processes. The difference between the sinking properties of the fiber and the shot is very great according to theory analysis and the test. From results of calculating and practical testing, the method of removing ceramic shots during manufacturing is put forward.

Synthesis of Xonotlite and Effects of Ceramic Fiber Addition on Its Compressive Strength

In order to improve the compressive strength of xonotlite, the pretreated quartz powder, slaked CaO, additive, deionized water(water-solid ratio of 30) were placed in a magnetically stirred autoclave, and the corresponding products were obtained after incubating at 220 ℃ for 0, 1, 3 and 6 h, respectively to explore the synthetic process of xonotlite. In the prepared xonotlite powder, 0, 5%, 10%, 15% and 20%(by mass, the same hereinafter) of pre-treated ceramic staple fibers were added, and two sets of specimen with the specifications of φ50 mm×35 mm were molded by pressed filtration.One set of specimens were not sintered, and the other group was fired at 1 000 ℃ for 2 h to explore the effect of ceramic fiber addition on the compressive strength before and after sintering of xonotlite. The results show that C-S-H gel is first synthesized in the synthesis of xonotlite, and then the C-S-H gel is transformed to form tobermlite, at last tobermlite fully reacts to produce xonotlite. The addition of ceramic fiber enhances the compressive strength of the xonotlite before and after sintering. When the 15% ceramic fiber is added, the compressive strength is the highest. The specimens before and after the high temperature firing contain xonotlite phase and calcium silicate phase, respectively, and the compressive strength of the fired specimens is higher than that of the green ones.

Application and practice of ceramic fiber block technology in industrial furnaces

Ceramic fiber,a kind of furnace lining material, is widely utilized in industrial furnaces. Fiber blocks can be made into various shapes. They have advantages of low thermal conductivity, low density and light weight for the development of industrial furnaces, This paper, taking a continuous annealing furnace as an example, describes the application of ceramic fiber blocks in the furnace and the installation methods. The temperatures of the furnace wall with different linings are analyzed. In the furnace design or the renovation of the existing furnaces, lining with ceramic fiber blocks is the preferred solution.

Optimization of Compressed Ceramics Fiber Insulating Layers

Compressed thin layers of ceramic fiber insulation are used as high temperature insulating layers as well as mechanical support for catalyst coated ceramic monoliths in automotive emission control devices. Minimization of energy losses, choice of material and thickness of com- pressed insulating layer are based on knowledge of their thermal physical properties. Currently, consistent meas- urements of materials in a compressed state, as they would be in emission control applications, are absent due to the absence of suitable methods for s,wh tests. A test method was developed for measurement of the thermal conductivity of compressed thin fiber layers. This paper summarizes the results of thermal conductivity and diffu- sivity measurements of 27 compressed fiber alumina -sili- ca -vermiculite materials in the range of 200 -950℃. Thermal physical properties as a function of temperature, density/mechanical pressure, thickness and composition of insulating layers are presented. The whole set of exper- imental data is generalized on 3D surface plots and de- scribed by polynomial functions. The possible heat trans- fer mechanisms governing apparent thermal conductivity of pressed insulation layers are discussed.

Single-frequency distributed Bragg reflector Tm:YAG ceramic derived all-glass fiber laser at 1.95 μm

A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,the threshold and linewidth of the single-frequency laser were measured to be 15.4 mW and 4.5 kHz,respectively.In addition,the measured relative intensity noise was less than-140 d B·Hz^(-1)at frequencies of over 10 MHz.The results show that the as-drawn Tm:YAG ceramic-derived all-glass fiber is highly promising for~2μm single-frequency fiber laser applications.

Silicon-Basing Ceramizable Composites Containing Long Fibers

Ceramization is a phenomenon which assures compactness of polymer-based composites in the case of their thermal degradation caused by open fire or exposure at high temperatures. This phenomenon is based on preventing volatiles of thermal decomposition of silicone rubber from evacuation by creation of ceramic layer. This ceramized structure is composed of mineral filer particles, connected by fluxing agent—glassy phase. The ceramic barrier created during firing is aimed to protect copper wire inside the cable from melting, being additionally strong enough to maintain integrity of electrical circuit. The paper presents experimental data on mechanical properties of silicone rubber composites strengthened additionally with long fibers of different types—aluminosilicate and polyamide (Kevlar) ones. Fibers were introduced into composites in oriented way. Mechanical properties were investigated taking into account fiber orientation anisotropy. Ceramization process of composites was described by observation of morphology and strengthen measurements of samples fired at 1000°C.

Effects of Ce^(3+) doping on the structure and magnetic properties of Mn-Zn ferrite fibers

Ce3+-doped Mn-Zn ferrite fibers were successfully prepared by the organic gel-thermal decomposition method from metal salts and citric acid. The composition,structure,and magnetic properties of these ferrite fibers were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),and vibrating sample magnetometer (VSM). The results show that Mn0.2Zn0.8Fe2-xCexO4 (x = 0-0.04) fibers are featured with an average grain size of 11.6-12.7 nm,with diameters ranging between 1.0 to 3.5 μm and a high aspect ratio (length/diameter). The Ce3+ ion doping has not resulted in crystal structural changes of the Mn-Zn ferrite phase and all the as-prepared ferrite fibers have a simple spinel phase structure,although this influences the morphologies of Mn0.2Zn0.8Fe2-xCexO4 ferrite fibers possibly owing to the lattice dis-tortion and internal-stress. Both the lattice constant and grain size increase slightly with the increase of the Ce3+ ion doping content. The soft magnetic properties of Mn-Zn ferrite fibers can be improved by a small amount of Ce3+ ion doping with an increase of the saturated magnetization and a decrease of the coercivity.

Effect of oxygen content on tensile strength of polymer-derived SiC fibers

Air-curing is usually applied to the polymer-derived SiC fibers and, as a result, oxygen is embedded to the material. An effective relationship between oxygen content of the SiC fibers and mass gain of their precursor fibers was established. Results also showed that oxygen content has a great influence on the mechanical properties and excellent tensile strength is usually obtained at the oxygen content of 12%～13%, similar to the density of SiC fibers. Oxygen content has a positive effect on the ceramic yield, and thus, is good to the density and tensile strength; while, oxygen content is also negative to volume content of SiC phase and crystallization of the SiC fibers, and thus, detrimental to the density and tensile strength. Both of the two effects result in the peak behavior of the tensile strength of SiC fibers.

Defects of Polymer-derived Si-C-O Fibers and Their Originations

Defects of polymer-derived Si-C-O fibers were intensively studied by the SEM and TEM techniques and their originations were also discussed on the basis of factors experiments.The defects were found mainly in the form of strumaes,pits and splits on surfaces as well as microflaw networks,porosity clusters and inclusions in the bulk.Factors experiments reveal that a nonuniform or an insufficient curing would result in larger-sized strumaes or interior microflaws.Gas evolution rates due to different firing rates have a great influence on the formation of internal microflaws or porosity clusters and some oxidation-induced pits or splits may be formed on surfaces because of a trace of oxygen or water vapor accumulated from the flowing inert atmosphere during pyrolysis.

Ceramic Wetlaid Nonwoven and Its Composite

The paper deals with the properties of wetlaid nonwovens and their composites in two different blended fibers (polyester and aromatic fiber pulp) and ceramic fiber pulp mainly. The conclusion is that high blending ratio of blended fiber will lead to the worse properties of the products.

ANALYSIS ON SMALL SCALE BRIDGING IN FIBROUS MONOLITHIC CERAMICS

Based on shear lag model of interface between fiber and matrix, a new formula that relates the crack opening displacement and bridging force in fibrous monolithic ceramics was constructed under the framework of small scale bridging. This formula was applied to predict the fracture resistance or R-curve response of a three-point bending specimen made of fibrous monolithic ceramics. A parametric investigation on the influences of fiber volume fraction, fiber radius, characteristics of constituents, BN's fracture toughness and specimen's geometry on the bridging forces and fracture resistance in Si3N4/BN composite was carried out. The upper and lower limits of the R-curve of Si3N4/BN in small scale bridging were derived. This research revealed the role played by the above parameters in the fracture toughness of fibrous monolithic ceramics.

A NEW METHOD TO DETERMINE THE R-CURVE OF CERAMICS-FRACTURE GRATING METHOD

The etching technique of the single-lined zero-thickness specimen grating is applied to the surface of the SiC fiber toughening Si3N4 ceramic composite specimen. The position of the crack and the crack length during the process of crack extension when the load is applied and gradually increased can be determined by recording the output voltage value of the Wheatstone bridge in which the ceramic specimen with the fracture grating on is located. The crack-growth-resistance(R-curve) of this material is thus obtained.

ZrB2-SiC spiral fibers prepared by combining liquid rope effect with non-solvent-induced phase separation method:A promising toughening material for ultra-high temperature ceramics

Spiral fibers were considered to be an ideal toughening phase of ultra-high torsional release effect.In this work,ZrB_(2)(Z)-20 vol%SiC(S)spiral fiber(ZS_(sf))with controllable structure was prepared by a combination approach of liquid rope effect and non-solvent-induced phase separation.Dominantly depended on the kinematic viscosity(η),dropping height(H),and flow rate(Q),the geometric parameters of ZS_(sf) involving filament diameter(d)and coil diameter(D)were followed the relationship of d≈0.516×10^(-3) Q^(1/2)H^(−1/4) and D≈0.25×10^(-3)(Q/H)^(1/3),respectively,within the optimizedηof 10-15 Pa·s.Three different microstructures of ZS_(sf) were achieved by adjusting the polymer/solvent/non-solvent system assisted with phase diagram calculation,including dense,hollow,and hierarchical pore structures.The ZrB_(2)-SiC with 1 wt%ZS_(sf) composites prepared by hot isostatic pressing(HIP)exhibited a~30%increase in fracture toughness(KIC,4.41 MPa·m^(1/2))compared with the ZrB_(2)-SiC composite,where the microscopic fracture toughness of the ZS_(sf) was~80%higher than that of the matrix.The fibers with a~10 nm in-situ-synthesized graphite phase amongst grain boundaries of ZrB_(2) and SiC changed the fracture mode,and promoted the crack deflection and pull-out adjacent the interface of matrix and the fiber.

Synergistic regulation of temperature resistance and thermal insulation performance of zirconia-based ceramic fibers

ZrO_(2) fiber is a promising high-temperature resistant and heat-insulating fiber material.However,the decrease in mechanical properties caused by grain growth at high temperatures seriously affects its application.How to achieve the synergy of its temperature resistance and the thermal insulation performance is still the focus of the current industry.In this work,we started with doping inequivalent elements and studied the phase composition,temperature resistance,and thermal insulation properties of Y_(2)O_(3)-ZrO_(2) ceramic fibers by adjusting the Y/Zr molar ratio.The results showed that Y_(2)O_(3) could enter the crystal lattice of ZrO_(2) and form a solid solution.With the increase in Y_(2)O_(3) content,the structure of fibers changed from a tetragonal phase to a cubic phase,and the configurational entropy of the system increased.The larger configuration entropy in the sample could produce a robust steric hindrance effect,inhibiting grain growth.After heat treatment at 1300℃,the grain size of Y_(2)Zr_(2)O_(7)(Y5Z5)fibers was only 61.8%that of Y_(0.1)Zr_(0.9)O_(1.95)(Y1Z9)fibers.The smaller grain size made the Y5Z5 fibers still have excellent flexibility and deformation recovery performance after heat treatment at 1300℃and could still return to the original state after 85%compression or folded in half.In addition,due to the larger configurational entropy,the mean free path of phonon scattering was shortened,thereby improving the thermal insulation performance of the fiber.In short,this work achieves the synergistic effect of temperature resistance and thermal insulation properties of zirconia-based fiber materials only through simple inequivalent element doping.