Thermal analysis of ceramic raw materials.pptx

This presentation is about thermal analysis if ceramic raw materials

1. Thermal analysis of ceramic raw materials Name:Ramavath Aryan Roll No:120CR0386

2. Introduction Ceramic Materials are… Inorganics Non-metallic Comprising metal and non-metal atoms by ionic and covalent bonds Generally formed out of a raw mixture by chemical/physical interaction Tuneable properties by processing (e.g. sintering ) Typicals properties of ceramic Materials are… High temperature stability High hardness Low ductility Poor electrical conductivity Chemical resistance

3. Based on their application…

4. Based on their composition…

5. Methods of Thermal Analysis

6. Thermogravimetry (TGA) is a technique in the mass of a substance is measured as a function of temperature or time while the substance is subjected to a controlled-temperature program in specified atmosphere. Product identification and characterization: Mass change Decomposition temperatures Thermal stability Compositional analysis Oxidation behavior Advanced Material Analysis: Decomposition kinetics Rate-controlled mass loss

7. Differential scanning calorimetry (DSC) is a technique in which the heat flow difference into a substance and a reference material is measured as a function of temperature while the substance and reference material are subjected to a controlled-temperature program Product identification and Characterization: Melting temperatures Transition enthalpies Phase transformations, Phase diagrams Crystallization temperatures Degree of crystallinity Glass transition temperatures Thermophysical properties : Specific heat capacity Advanced Materials Analysis: Decomposition effects Reaction kinetics Purity determinations

8. Measurement of TGA(mass change)and DSC(caloric effects) on One sample in One measurement in One system. Comparability of the results is given: No influence of materials inhomogeneity No influence of measurement conditions Shorter measuring times

9. Experimental Parameters Sample mass 40mg heating rate 10K/min 100 % CO2 Atmosphere

10. Experimental Parameters Sample mass 40mg heating rate 10K/min Air Atmosphere

11. NICKEL CARBONATE The thermal behaviour of pure basic nickel carbonate, ammonium molybdate and their mixtures in different ratios were studied by means of TG,DTG, and DTA analysis. Relative thermal analysis (RTA) graphical treatment of derivatographic curves of the components in the pure and binary system has been carried out. X-ray diffraction (XRD) analysis and infrared (IR)spectroscopy were used to characterize the solids produce from thermal treatment at temperature ranges between 250˚c and 1000˚c. The results obtained revealed that pure nickel carbonate decomposed into Nio at 250˚c,while pure ammonium molybdate decomposed into Mo03 at 340˚c and then melted at 790˚c.crystalline(NH4)4Mo8o26 and (NH4)4Ni4(NH3)3MO5O20 phases were detected for mixtures pre-calcined at 250˚c. For the binary component, crystalline nickel or molybdenum oxides were detected beside nickel molybdate phase starting from 500˚c. The latter phase was formed as a result of solid-solid interaction and its formation is exothermic in character. The calcination temperature and composition of the mixture directly affect the formation of NiM0O4 phase. The compound formed is thermally stable up to 1000˚c. The presence of two components solid in the binary system affected the thermal decomposition of their individual salt and affected their physical and chemical behaviour

12. SILICA Silica is second only to clay in significance as a ceramic material and it is the most abundant mineral in the earths crust, The principal siliceous materials are: crystalline Quartz, Quartzite, sand stone, silica sand, “organic” and amorphous silica:including flint and diatomaceous earth, silica is frequently referred to as “potters flint” and is often just ground sand stone, it is used interchangeably with quartz. Silica or quartz is used in clay bodies to modify shrinkage, porosity and strength. Quartz has a phase transition at 1063f i.e. the quartz inversion. Upon firing, this inversion occurs rapidly and results in volume expansion, which can lead to firing cracks in clay bodies high in free quartz. In glazes, silica is the most common glass former. It serves to control the fusibility and viscosity, which are dependent on the amount of silica in the glaze. Typical mesh size of 200(>74microns),325(>45 microns) and 400 (>30 microns) are offer varying applications in clays bodies and glazes, the coarser 200 mesh helps to control shrinkage while the finer 325 and 400 mesh are useful in glazes for their reactivity and ease of going into solution.

13. THERMAL ANALYSIS OF CLAY Clay minerals are highly susceptible to significant compositional changes in response to subtle changes in the fugacity of water affect the stability of interlayer H2o in clay mineral. Differential thermal analysis (DTA), thermal gravimetric analysis (TG or TGA), and derivative thermal gravimetric (DTG) analysis are reported for each of the eight source clay minerals using commonly available commercial instruments. The DTA curves show the effect of energy change in a sample. For clays, endothermic reactions involve desorption of surface h2O ( e.g. interlayer H2O) at low temperature (100c), dehydration and dihydroxylation at more elevated temperature, and, eventually, melting. Exothermic reactions are related to recrystallization at high temperature that may be nearly concurrent with or after dihydroxylation and melting. Discriminating between desorption or dehydration and dihydroxylation may be problematic. The TG curves ideally show only weight changes during heating. The derivative of the TG curve, the DTG curve, shows changes in the TG slope that may not be obvious from the TG curve. Thus DTG curve and the DTA curve may show strong similarities for those reactions that involve weight and enthalpy changes , such as desorption, dehydration and dihydroxylation reaction.

14. POTASSIUM FELDSPAR Advance on thermal decomposition of potassium feldspar with flux agents are reviewed. Thermodynamic calculation shows that the temperature range of the thermal decomposition of potassium feldspar is 800-890c with stoichiometric additives of sodium carbonate or potassium carbonate. Analysis on the mechanism of thermal decomposition reaction shows that with increasing the calcination temperature, potassium feldspar passes through a stage predominated by decomposition and sinter simultaneously. Decomposition proportion of various potassium feldspar powder materials determined are over 98%. This shows that with stoichiometric additive of sodium carbonate or potassium carbonate, the potassium feldspar can be decomposed at 820- 850˚c

15. Thermal Analysis of Kaolin The sample is dried and solidified at room temperature after the water is added and mixed. The sample is heated at 20c/min from 30 to 1500c in air atmosphere in a platinum open pan. 40mg of powder sample is prepared on measurement sample pan after the dried sample is crushed into powder. For TMA measurement, the sample is heated from 30 to 1500˚c at 5c/min in an air atmosphere. Load is 20mN. Alumina ceramics probe and sample cylinder are used. Dried sample is cut off 7mm rectangular and stayed vertically. Load setting for TMA measurement is usually 100mN. However as it is really weak against the load, the load value is set small. Figure 1 :DTA curve shows endothermic peak in the around of 600c and exothermic peak in the around of 1000c. TG curve shows weight loss in the expansion up to around of 450c. TMA curve shows the expansion up to 1400c. Figure 2 :from room temperature to 200˚c. DTA curve does not show any changes but TG curve shows slight 0.36% weight decrease until 150˚c. TMA curve shows only 0.1% expansion . The reason of 0.36% is likely by the water evaporation. Adhesion water is the residue when dried, or the one which vapor is adsorbed on kaolin powder after dried. Moisture absorption characteristic of kaolin powder can be identified by the amount of adhesion water. Slight expansion is the thermal expansion caused by temperature increase. Figure 3: shows the extended figure for the range of 300 to 900˚c. DTA curve shows broad endo thermic peak at 574˚c. TG curve shows 11.6% weight decrease. TMA curve shows 0.7% shrinkage. In this range of temperature, structured water of kaolin dehydrates which causes endothermic, weight decrease, and shrinkage and makes various unique curves. The amount of the dehydration varies up to the composition of kaolin . The information such as weight decrease ratio and compounding ratio can be achieved.

16. Figure 4 :shows the extended figure for the range of 900 to 1050c. DTA curve shows sharp exothermic peak at 1002c. TG curve does not show any changes. TMA curve shows slight 1.3% shrinkage. In this range of temperature, exothermic heat and shrinkage likely occur because of the crystallization of alumina and silicic acid. It not cause weight change as the crystallization keeps mass. The measurement shows sharp exothermic peak. The temperature, size, and shape of the exothermic peak varies greatly depending on where kaolin is extracted. There is a difference in temperature in exothermic peak in DTA curve and shrinkage in TMA curve. It is caused by the different in heating rate between that of TG/DTA and TMA. For TMA measurement, as the sample size is big, the temperature distribution in the sample becomes wider in the same heating rate as TG/DTA. Thus the heating rate is reduced to make temperature shifted to the low temperature. Figure 5 :shows the extended figure for the range of 1050 to 1500c. DTA curve does not show any changes. TMA curve shows 14% shrinkage. In this temperature range, mullite and cristobalite are formed which causes exothermic heat and shrinkage. It does not cause weight change as the mass is kept. The shrinkage ratio in this temperature range is biggest. In case it is used as the material of ceramic, shrinkage ratio has to be considered before it is fabricated. Measurement of the shrinkage ratio by TMA can be a valuable part of fabrication process.