Infrared Image Furnace Research Articles

A fast-firing shrinkage rate controlled dilatometer using an infrared image furnace

A novel dilatometer design is described for performing rate controlled sintering experiments on powder compacts. Previous rate controlled sintering systems, which control the shrinkage of a sintering compact, possessed only limited shrinkage rate control and shrinkage profile complexity due to the high thermal mass of conventional furnaces and dilatometers. The instrument described in this work features an infrared imaging furnace and a low thermal mass dilatometer assembly which together provide a very rapid temperature response. The system is capable of heating and cooling ceramic samples at up to 500 °C/min. Shrinkage control is accomplished using a modified, computer interfaced proportional-integral-derivative algorithm, and tests on glass–alumina composite samples demonstrated excellent shrinkage control with differences routinely less than 0.2% between the set point and actual shrinkage.

Superconducting properties of doped and off-stoichiometric Bi 2Sr 2CaCu 2O 8 single crystals

High quality single crystals and grain aligned rods of off-stoichiometric Bi-2212 superconductor have been grown by the ‘floating zone’ method using an infra-red image furnace. Growths starting from off-stoichiometric compositions have been performed to optimize the size of the crystals and their superconducting properties. Aligned rods and single crystals of the Y doped compound, Bi 2.2Sr 1.64Ca 0.96Y 0.2Cu 2O 8, have also been grown successfully and characterized. The effects of annealing and oxygen stoichiometry on the superconducting properties of these crystals are presented.

Single crystal growth of Bi2Sr2CaCu2O8 using an infra-red image furnace

Large aligned rods and high quality single crystals of the superconductor Bi 2 Sr 2 CaCu 2 O 8 have been grown by the floating zone method using a double ellipsoidal infra-red image furnace. Several growths have been performed starting from different compositions. The crystals produced are of extremely high quality; the best crystals exhibit superconducting transitions at around 93 K.

Phase Equilibria and Properties of Glasses in the Al<sub>2</sub>O<sub>3</sub>-Yb<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> System

Phase diagrams of the Al2O3-Yb2O3-SiO2 system and the properties of glasses in this system were investigated. The results are summarized as follows:(1) Phase diagram of the 3-component Al2O3-Yb2O3-SiO2 system at 1550°C and those of the three types of 2-component Yb2Si2O7-Al6Si2O13, Al1.25Yb0.75O3-SiO2 and Al1.44Yb0.56O3-SiO2 systems were established and the region where the liquid phase exist at a high temperature was clarified. The lowest solidus temperature in the present system is 1500°C.(2) The glass-forming region of the Al2O3-Yb2O3-SiO2 system was clarified by quenching the melt in an infrared image furnace(3) The glass transition temperature of the present glasses is in a range of 880-895°C. The onset and peak temperatures for crystallization are in a range of 975-1040°C and 1070-1230°C, respectively. They tend to increase as the SiO2 concentration is increased.(4) In the 2-component Yb2Si2O7-Al6Si2O13 system, the peak temperature for crystallization and the activation energy for crystal growth attain a maximum at a composition near the eutectic composition.(5) Analyzing the infrared spectra of glasses, it is suggested that Yb ion is mainly a network modifier in glassses.(6) Solidus temperature of the Ln2Si2O7-Al6Si2O13-SiO2 system (Ln=Dy, Er, Gd, La, Nd, Sm, Y, Yb) tend to increase as the radius of rare-earth ion decreases. The system with Yb has the highest solidus temperature among them.

Pyrolysis of methane into higher hydrocarbons on carbon fiber in a thin flat tube of quartz heated by an infrared image furnace

Pyrolysis of methane over pitch-based carbon fiber (CF) was studied, using a thin flat quartz tube reactor heated in an infrared (IR) image furnace. The pyrolysis produced ethane as the dominant product when the conversion was below 1%. Increasing conversion by additional CF or lower flow rate increased the selectivity for ethylene first, and then acetylene and pyrolytic carbon. C 3 and C + 4, principally C 4, hydrocarbons were always minor products, indicating the consecutive nature of the reaction. The maximum yields of C 2 and C 2C + 4 hydrocarbons were 7.5 and 9.2%, respectively, at a conversion of 10%. The conversion stayed constant with increasing concentration of methane, indicating a first order reaction in methane; however selectivity varied with the concentration, suggesting that bimolecular reactions govern the product selectivity. It should be noted that there was no production of tar or carbon on the reactor wall in the present pyrolysis. The CF surface may initiate the CH fission of methane and assist the termination of chain reactions to produce C 2C 4 hydrocarbons at rather high selectivity.

北海道産マンガン土の加熱放出ガスによる研究

This paper describes released gas analysis of manganese wad from Akan, Kogane and Niimi. The samples were heated by the infrared image furnace in He gas condition, and mass spectra of released gas phase were measured by Q-mass spectrometer. Experimental results show that(a) the detected phases on heating are H2O, N2, O2 and CO2, (b) the volume of CO2 mainly depends on the species of manganese mineral, and(c) O/Mn ratio of manganese wad was varied widely and there is a negative correlation between O/Mn ratio and crystallinity. The above features are mostly depend on the amorphous part of the managanese wad. As X-ray diffraction method is insufficient for amorphous phase, gas analysis can provides an important data for study of manganese wad. Manganese wad from Akan (Akan-2) shows unique charactaristics.(a) Akan-2 does not release O2 gas on heating in He gas condition.(b) The structure deforms on heating at 42°C.(c) The DTA data shows a exothermic peak at 300°C.

両端自由衝撃曲げによる構造用セラミックの高温衝撃破壊じん性の計測

A new instrumentation system was developed for the measurement of dynamic fracture toughness of ceramic materials at elevated temperatures up to 1200 deg C by impact test with a free end bend specimen (one-point-bend specimen). The specimen was of Charpy type (6mm width, 8mm height and 50mm length) made of silicon carbide (SiC) and a notch of 0.2mm width was cut by a diamond wheel. The specimen was hanged in an infrared image furnace by a couple of thin ceramic threads cemented onto the end surfaces of the specimen. Thus the heat conduction that usually takes place through support structure could be avoided or kept to a minimum. The impact force was provided by a falling steel cylinder of 6mm dia and 1500mm length with a pair of semiconductor strain gauges cemented onto a cylindrical surface to measure the stress wave history and hence to determine the impact force. Since the thin threads are thought to be broken at the moment of impact, the specimen is supposed to fracture without any constraint at both ends.A simple formula was employed for determining the dynamic stress intensity factor from the measured impact force with a microcomputer used for processing the experimental data. A series of impact tests were performed with drop-height increased gradually and the dynamic fracture toughness was determined from the test data of the minimum drop-height that caused specimen fracture.The dynamic fracture toughness values obtained by the impact test were compared with the results of quasi-static tests. It was shown that the developed system is satisfactory for measuring the dynamic fracture toughness of ceramic materials at elevated temperatures.

Thermal cycling test of titanium in deuterium atmosphere

Thermal cycling tests of titanium in deuterium atmosphere were carried out with an infrared image furnace in a constant volume system. No change in the surface microstructure of the titanium specimen was observed after thermal cycles between 800 and 600°C whereas thermal cycling between 800 and 250°C caused microcracking along the grain boundaries of α-titanium on the surface of the specimen. From metallographic observations of the cycled specimens, it was found that the morphology of deuteride precipitation in the specimen strongly depended upon temperature range of cycles. The number of cycles was found to affect the distribution and orientation of deuteride precipitations. Decrease in the heating and cooling rates resulted in more oriented deuteride precipitates. The isothermal desorption behavior of the cycled titanium specimen was also studied by comparing with that of non-cycled titanium. Above the desorption temperature of 600°C, no marked difference in the desorption behavior could be observed for either cycled or non-cycled specimen. However, at relatively lower temperature, the desorption rate for the cycled specimen was considerably lower than that for the non-cycled specimen.

Preparation of Li 3N single crystal by floating zone technique

Single crystals of the superionic conductor, Li 3N, have been prepared by a floating zone technique in an infrared imaging furnace. The following peculiar shape transformation of the single crystal is observed: The cross-section of the single crystal at the solid-liquid interface is round. However, it is square at a position about 20 mm below the molten zone. As a result, a single crystal in the shape of a square prism and with dimensions of 9 × 9 × 60 mm 3 was obtained. Impurity oxygen as well as hydrogen was detected in the crystal, which could possibly enhance the ionic conductivity. The crystals shows thehighest ionic conductivity ( σ ⊥ c) = 2.0 S m −1 at 300 K) and the smallest activation energy for Li + ion transport ( E a = 0.15 eV) ever known on this material.