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Tham khảo tài liệu 'introdution to thermal analysis techniques and applications part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 112 TD has also been used X to study the sintering behaviour of kaolins and kaolmitic clays. On healing kaolin loses structural water al about 550 c and forms the mclakaolin structure. Above 96ÍTC this converts to a spinel structure and then above I lux to mullite. The mullite formed sinters at higher temperatures. These reactions arc accompanied by the shrinkages shown in Figure 6.7. The TD curves of kaolins and kaolinilic clays may be used for lheir classification x Figure 6.7 Thcrmodilatomctry curve of kaolin based on Fisher Scientific Co. Bull. 156 p 4. with permission . Ollier applications of TO include studies of the effects of additives on the shrinkage of cellular concretes 9 the defects in non-stoichiomeiric oxides 10 the firing of ceramic s and the properties ofalloys III 6.3 Thcrinomechiinical njilysis TMAl Static Force Thermomcchanometry sf TNI 63. J Principle Í 2 Static Force Thermomechanometry tor Static Force Thermomechamcal Analysis. sf-TM A will be more easily recognised by Its less systematic but well-established name ThCTmomechanic.il Analysis TMA Thermodilatometry is carried out by measuring expansion and contraction under negligible loads. Further information of interest may be obtained by measuring the penetration i.c. the expansion or contraction of a sample w hile under compression as a function of temperature. Alternatively the extension i.c. the expansion or contraction of a sample under tension may be measured as a function of temperature. These techniques plus flexure and torsional measurements arc classified as thermomcchantcal analysis TMA and are obviously of great practical importance in materials testing sec applications . 113 6.J.2 Practical dr tails The apparatus used is based on that or thcnnodilatomctry Section 6.2 . The principles of penetration extension flexure and torsional measurements are illustrated in Hgure 6.x. Figure 6.8 Thcrmomcchanical analysts TMA a penetration b extension c flexure and d torsional measurements 114
