Experimental study of the thermal conductivity of heat insulation materials based on expanded vermiculite

Abstract

Results are presented for experimental studies of the thermal conductivity of expanded vermiculite. Tests are performed in an experimental test unit by a steady-state heat flux. Thermal studies are carried out in the range 300 -1100 K. It is shown that thermal conductivity increases uniformly with an increase in temperature. The most probable reason for an increase in thermal conductivity is the effect of heat radiation. Results are provided for an approximate second power polynomial.

Expanded Perlite, Expanded Vermiculite and Microspheres as Fillers in New Generation Paper Pulp Mixtures Used for Contact With Liquid Metal

“…The current knowledge of the expanded vermiculite [17][18][19][20][21], expanded perlite [22,23], and microspheres [24,25] proves their higher thermal resistance when compared to the cellulose based unmodified materials [11,12]. The exothermic effect for the commercial cellulose sample and the experimental #1 one is connected with the occurrence of microspheres which, to a certain temperature level, behave as an admixture improving the insulation ability of the mixture, whereas after exceeding the limit temperature they trigger exothermal effects [12,15,16].…”

Gas Evolution Quantitative Analysis at a Temperature of 900°C of a Cellulose Mixture Modified by Mineral Additives

“…Owing to their thermal resistance [15][16][17][18][19]22], which is higher than that of the commercial mixture [2,9], materials for the pulp modification used in the study give the experimental mixtures a thermal resistance comparable to that of commercial products [20,21], while at the same time reducing gas evolution. This effect can be attributed to the temperatures characteristic of the additives used in the study.…”

“…The gas evolution was measured at a temperature of 900°C +/-2°C. The test samples were placed inside a preparation chamber (16) at room temperature and subsequently the whole measurement chamber (9) was blown throughout with nitrogen for 120 seconds. After a neutral nitrogen atmosphere was obtained, the vent valves and inlet valves were shut (18)(19).…”

“…Different ceramic materials, which may have some disadvantages, but which contaminate the moulding compounds and prove difficult in mechanical treatment, are usually used to make casting systems for large and medium-sized casts. This paper presents a gas evolution study of a cellulosebased mixture obtained from waste paper with the addition of minerals resistant to high-temperature, such as expanded perlite, expanded vermiculite and microspheres [14][15][16][17][18][19]. Being materials of high thermal resistance, the additives modify the thermal resistance parameters of the cellulose-based mixture.…”

Gas Evolution Qualitative Analyses From Modified Cellulose Mixtures During Thermal Degradation in Air and Argon

“…This paper analyses the thermal degradation of a novel mixture patented by the authors [24]. This cellulosebased mixture was modified with natural additives, such as expanded vermiculite [4,5,8,15,16], expanded perlite [1,10,18,20] and microspheres [2,6,7]; inorganic resins were used as a binder [3,9]. Expanded perlite and vermiculite have very interesting physicochemical properties, such as: large absorption capacity for liquids, low bulk density, high thermal resistance of a neutral chemical nature and negligible chemical reactivity.…”