The Effect of Thermal Treatment on the Characteristics of Porous Ceramic-Based Natural Clay and Chitosan Biopolymer Precursors (original) (raw)
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International Conference on Smart Materials and Nanotechnology in Engineering, 2007
Hydroxyapatite (HA) porous materials for artifical human cancellous bone applications have been prepared via polymeric sponge method. Suspensions of the nanostructured hydroxyapatite powders were prepared with a fixed amount of distilled water and HA loading. After soaking cellulosic sponges into the suspension, the sponges were dried and then subjected to heat-treatment at 600°C, followed by sintering at 1250°C for 1 h. No alteration in structure found after sintering. The effect of sintering rate on the physical properties was also investigated in the study on two samples prepared based on a HA loading of 44% in the starting slurry. The study found that the average apparent density of the porous bodies were 2.03 g/cm 3 and 1.69 g/cm 3 with porosites of 36 and 46 % for the faster and the slower sintering, respectively. Morphological evaluation of the porous bodies shown that both the samples contained macropores of 200-500 µm diameter, which fulfill the minimum pore size of 100 µm as medically required. Excellent pore interconnectivity was found in all the samples. The measurement of compressive strength provided the values of 10.0 and 4.3 MPa for the faster and the slower sintering, respectively. It was also shown that the difference in sintering rate influenced the crystallinity of porous HA obtained.
Development Of Porous Ceramic Clay Bodies Using Four Different Types Of Bioresource Wastes
2014
The main objective of this study is to ascertain the possibility of fabricating porous clay ceramic materials. The raw materials consist of a kaolinitic Laotian clay and an illitic Malaysian clay, mixed with bioresource wastes (kenaf powder, kenaf fiber, banana stem and sugarcane wastes) as the pore-forming agents (PFA). The raw powders, i.e. Laotian clay (LC), Malaysian clay (MC) and bioresource wastes were initially characterized using XRF, XRD and TGA/DSC. The clay ceramic green bodies were fabricated with different types and amounts of bioresource wastes in the clay bodies (10, 20 and 30 wt%). The granulated powder mixtures were pressed hydraulically using a round stainless steel mould 23 mm diameter, under a pressure of 50MPa. It was observed that different types of bioresource waste additions did not create any shaping problems. After drying, the ceramic green bodies were fired at different temperatures (1100, 1125, 1150 and 1175oC) for 3 hours at a heating rate of 5oC/min. Th...
Determination of Sintering Temperature in Synthesis of Gelcasted Porous Ceramic
2017
The aim of this study was to determine the temperature of gelcasted ceramic to obtain maximum pore. Pore formation occurs when the polymer system in ceramic body is being degraded. Polymer used was acrylamide (AM) with crosslinker methylen bis acrylamide (MBAM) and the raw material was natural clay. The method of synthesis porous ceramic was gelcasting method which produce polymer in the slurry as a green body ceramic. Determination of sintering temperature using TGA / DTA method. Based on the analysis, the sintering process of gelcastedcrude ceramic body was carried out at the temperature of 28 °C 1100 °C with a certain treatment of temperature and time. The sintering process using heating rate of 50 o C/15 minutes with 60 minutes detention at the temperature of 100 °C, 200 °C, 500 °C, and 1100 °C. IndexTerms—Clay, Ceramics, Gelcasting, Sintering __________________________________________________________________________________________________
Microstructural Characterization of Porous Clay-Based Ceramic Composites
Materials, 2019
Clay-based materials are the most traditional components of buildings. To improve their performance in a sustainable way, agents can be mixed to fired clay acting as a pore-forming factor. However, firing temperatures highly influence their microstructure which is closely linked to a material’s final performance as a ceramic block. To highlight the influence of the firing temperature on microstructure, and more specifically on the pore size distribution of clay-based materials, three innovative porous materials were manufactured. These materials were produced by mixing clay and pore-forming agents. They were characterized by optical and scanning electronic microscopy, x-ray diffraction, mercury intrusion and nitrogen adsorption. These techniques allow the phase identification of materials, show sample microstructure and quantify the pore size distribution at different scales. Furthermore, geometric parameters of sample microstructure such as grain diameter and roundness are estimate...
Preparation and characterization of clay-based porous ceramics with boric acid as additive
Ceramics International, 2014
Intention of this work was to obtain porous silicon dioxide ceramics by using boric acid as an inexpensive additive at low forming pressure and low sintering temperature. Starting raw material, smectite clay from surface coal mine Kolubara, Serbia, was purified from organic and inorganic impurities by using heat and chemical treatment. Boric acid was used as binding and sintering aid in amount of 0.5, 1 and 2 wt%. Powder was compacted by using different pressures: 40, 60 and 80 MPa. Pressed samples were sintered at 850, 1000, 1150, and 1300 1C for 4 h in air. A relatively high porosity of nearly 40% is obtained for the samples pressed at 40, 60 and 80 MPa and sintered at 1000 1C. Median pore size diameters are in the range of macroporous up to 0.2 μm and 10 μm in the samples sintered at 1150 and 1300 1C, respectively. X-ray diffraction (XRD), scaning electron microscopy (SEM), and porosimetry measurements were employed to characterize the phases and microstructure of the obtained ceramics. The relations between mechanical characteristics of samples (Young modulus and Poisson ratio) and content of boric acid were studied.
Physical and mechanical properties improvement of a porous clay ceramic
Applied Clay Science, 2017
This work deals with the chemical, physical, thermal and mechanical analyses of porous clay and non-plastic clays mixtures from Tunisia. Five mixtures which are M1 (70 mass% clay +30 mass% waste brick), M2 (70 mass % clay +15 mass% waste brick +15 mass% sand), M3 (70 mass% clay +30 mass% sand), M4 (70 mass% clay + 30 mass% chamotte) and M5 (70 mass% clay + 15 mass% chamotte +15 mass% sand) were sintered between 900 and 1100°C and were evaluated for their possible ceramic applications. Thermal analysis (DTA/TG), dilatometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and physical-mechanical analyses (tensile strength, water absorption and bulk density) were used to assess the thermal behavior, phase evolution and microstructure of the fired mixtures. The formations of both the anorthite phase and the vitreous phase have improved the required ceramic product performance. M1 has the highest values of tensile strength and bulk density at 1100°C. According to the European Norm EN 14411, all the mixtures belong to the BIII group which are suitable for the production of earthenware and unglazed stoneware.
Comparison of Three Manufacturing Techniques for Sustainable Porous Clay Ceramics
Materials
This study proposes different manufacturing techniques (manual pelletization, powder pressing, and “shell scaffold”) to obtain lightweight clay ceramics containing recovery raw materials. The sintering in an electrical furnace (1000 °C, 1 h processing time) was conducted by traditional firing from room temperature, for pressed and shell-scaffold samples, while the flash heating (i.e., samples directly put at 1000 °C) was used only for the pellets. The porous materials (porosity 40–80%), functionalized with nutrients (K and P) in amounts to confer the fertilizer capability, gave suitable results in terms of pH (6.7–8.15) and electrical conductivity (0.29–1.33 mS/cm). Thus, such materials can be considered as feasible lightweight clay ceramics, with a positive effect on the soil. These findings permit us to hypothesize a potential use in green roofs or in agronomic applications.
Fabrication and Microstructure of Clay-Based Geopolymer Ceramic Using Powder Metallurgy Method
Applied Mechanics and Materials, 2015
Geopolymers can be transforms into ceramics upon sintering. This paper reports the effect of temperature on the mechanical properties and microstructure of Na based kaolin geopolymer ceramic. The Na 2 O.Al 2 O 3 .4SiO 2 was fabricated through powder metallurgy method. The geopolymers samples were exposed to temperature from 900 °C up to 1200 °C. The relative density, total porosity and flexural strength of sintered sample ranged approximately 84%-95%, 5.04%-15.73% and 20-70 MPa respectively. SEM analysis on as-sintered sample showed glassy phase while polished sample showed the pore structure and distribution. XRD results showed that nepheline appeared in all heated samples. Samples heated to 1200 °C achieved highest flexural strength and toughness of 70MPa due to the optimum density.
Factors affecting the microstructure of porous ceramics
Journal of the Serbian Chemical Society, 2006
In this study, porous ceramics were produced by using two methods: the polymeric sponge and foam method. A study of the effect of viscosity on the characteristics of the final product produced using the polymeric sponge method revealed that the microstructure of porous ceramics is highly affected by the viscosity of the slurry. The optimal ratio between porosity and the strength of the porous material was achieved by subsequently repeating the immersing and drying processes. A study of the porous material obtained using the foam method revealed that the pore size and foam volume can be controlled by varying the amounts of anhydride and thermal blowing agent. The problem related to foam collapsing was solved by using a thermal blowing agent. The microstructure of the samples was characterized by SEM.
A Review of the Development of the Gel Casting Method for Porous Ceramic Fabrication
RASAYAN Journal of Chemistry
The objective of this paper is to present an overview of the development of gel casting methods on synthesis techniques and the characteristics of gel casting porous ceramics and its applications. The gel casting method is a colloidal ceramic synthesis method that requires a short period for the ceramic body to develop. This review provides the latest developments in the gel casting process of synthesizing porous ceramics. At the beginning of the gel casting method development, the acrylamide (AM) system was the most commonly utilized system. Over time, the use of the AM system began to be minimized because of its toxicity. Researchers began to develop natural polymers as pore templates and natural minerals as raw materials in the gel casting method. In addition to polymers and raw materials, the gel casting process also requires additives such as gelling agents and dispersants. At the end of this review, a mapping of how to select the additives in the gel casting process, for AM sy...