Phase diagrams and decomposition for systems of (C 2H 5) 2NH·HCl C 6H 10 O 4 (adipic acid) and (C 2H 5) 2NH·HCl C 10 H 18 O 4 (sebacic acid) have been investigated by DTA, DSC and visual polythermal methods. Both two systems are of the simple eutectic type. Eutectics are located in 50% of C 6H 10 O 4 at 94 ℃ and 55% of C 10 H 18 O 4 at 106 ℃ respectively. (C 2H 5) 2NH·HCl melts at 217 ℃ and decomposes as soon as it just melted. A polymorphic reaction of (C 2H 5) 2NH·HCl occurs at 98 ℃, the transition heat is 29.7 J/g. Experiments also revealed that adipic acid melts at 152.8—155.7 ℃ with melting heat 199.1 J/g, decomposes at 250.8—263.0 ℃ with decomposition heat 174.2 J/g; sebacic acid melts at 133.1—135.9 ℃ with melting heat 199.8 J/g and decomposes at 233.2—269.2 ℃, but no exact value of decomposition heat has been determined. [WT5HZ]
The growth characteristic of intermetallics during the reaction of solid (Cu,Ag,Au,Fe,Co,Ni,etc) with liquid (Sn,Sb,Bi,Zn) within a very short time of 1～ 2 s at different temperatures has been studied by metallographic method for explaining the process in the fillet during soldering. It is indicated that the incongruent compourds often grow up as bamboo shoot form. But congruent compounds grow up basically just by spreading out as a layer along the solid border. Base on these facts,the influence of intermetallics in the fillet during soldering has been discussed.
