Application of thermal analysis in solidification pattern control of La-inoculated grey cast irons

Journal of Thermal Analysis and Calorimetry - The new generation of acid-lined medium-frequency coreless induction furnaces revolutionized the iron foundries, resulting higher overheating and lower...     

Simultaneous thermal and contraction/expansion analyses of cast iron solidification process

Journal of Thermal Analysis and Calorimetry - Simultaneous thermal and contraction/expansion analysis of hypoeutectic grey (lamellar graphite) and ductile (nodular graphite) cast irons...     

Application of thermal analysis to monitor the quality of hypoeutectic cast irons during solidification in sand and metal moulds

By exploring the effects of carbon equivalent (CE?=?3.4?C4.2%) and inoculation (Ca, Ba, Al?CFeSi alloy), the thermal analysis parameters, representative temperatures and undercooling events, during solidification of cast irons are compared with chill tendency (carbides) in cast irons. Cooling curve analyses were conducted directly in the thermal centre of samples solidified in resin sand and metal moulds to explore the utility of thermal analysis in actual casting shapes. As a reference, a Quik-cup? system was employed with the same cooling modulus (CM?=?0.75?cm). The austenite formation temperature is lower at higher CE, with higher temperatures of both the start of the eutectic reaction and end of solidification. This was more pronounced for metal mould solidification and for un-inoculated irons, respectively. The transition from white iron through mottled iron up to grey iron macrostructure is illustrated by variations of eutectic undercooling compared to the metastable equilibrium temperature, as affected by increasing carbon equivalent and applied inoculation. Inoculation affected both austenite and eutectic formation, by preventing excess eutectic undercooling during solidification, even at low carbon equivalent. The differences in solidification patterns of sand and metal mould castings are discussed, for un-inoculated and inoculated irons, at different carbon equivalent values.     

Application of cooling curve analysis in solidification pattern and structure control of grey cast irons

In this article, the composites based on long glass fibre reinforced polypropylene/intumescent flame retardant (LGFPP/IFR) were prepared by melt blending. The influence of thermal oxidative ageing on the LGFPP/IFR composites with different thermal oxidative ageing time at 140 °C was studied by means of oven heating. The thermal stability and flammability of the composites were respectively investigated by thermal gravimetric analysis (TG), limiting oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), scanning electronic microscopy (SEM), mechanical properties test and energy-dispersive X-ray analysis (EDAX). A trend of increase first and then decrease in LOI values was shown in 0–50 days ageing, with the same trend as thermal stability obtained from TG in nitrogen condition. The CCT results indicated that the LGFPP/IFR composites after ageing achieved a higher heat release rate, which means a higher fire risk. The mechanical properties showed a global decrease in just 10 days ageing. Morphologies obtained from SEM showed that both the rupture of PP matrix and fibre interface debonding led to the decrease in mechanical properties. The EDAX proved that IFR particles could emerge and gather on the surface of sample in ageing procedure, which had great effects on the thermal stability and flame retardancy of the composites.