Excellent High-temperature Characteristics Research Articles

Ultrahigh temperature and ultrahigh speed operationof1.3 µm strain-compensated AlGaInAs/InP uncooled laser diodes

High performance 1.3 /spl mu/m uncooled lasers with excellent high temperature and high speed characteristics are reported. A CW characteristic temperature of 105 K between 25 and 85/spl deg/C, a maximum CW operating temperature above 170/spl deg/C, and an intrinsic 3 dB modulation bandwidths estimated at /spl ges/23 GHz at 25/spl deg/C and 15 GHz at 85/spl deg/C, have been achieved. These values are among the best obtained for 1.3 /spl mu/m AlGaInAs laser devices. >

Microstructure and mechanical properties of Al-Al2O3-MgO cast particulate composites

Al-Al2O3-MgO cast particle composites prepared by an MgO coating technique were investigated for their microstructural and mechanical property features. In all, sixteen compositions of the composite were subjected to this study. Generally, a uniform distribution of Al2O3 particles was observed in the composites. But in the upper half portion of the cylindrical castings, Al2O3 particles were found to segregate along the grain boundaries and also within the grain-forming chain-like structures. The microhardness of the base matrix revealed that the retention of submicrometre MgO particles causes dispersion strengthening. In the case of maximum strengthening, the microhardness of the base matrix rises to 35 kg mm−2 from 19 kg mm−2 for as-cast pure aluminium. The composites also displayed excellent high-temperature tensile properties up to 250°C (523 K). At the level of 21%V f retention of Al2O3, the composite displayed a UTS value of 110 MN m−2 with corresponding 0.2% offset yield strength of 65 MN m−2 and 12% elongation at ambient temperature. At 150° C (423 K) and 250° C (523 K), the composite retains 69% and 53%, respectively, of its room-temperature UTS value. This was the optimum retention of Al2O3 and the best composite obtained in the present work. The excellent high-temperature characteristics of the composite are thought to be due to the sum total effect of both the submicrometre MgO particles and the coarser Al2O3 particles retained in the aluminium base matrix.

SULPHENE INTERMEDIATES IN THE SYNTHESIS OF POLY(P-BENZENE-SULPHONAMIDES) AND POLY(P-BENZENE SULPHONATES)

Abstract Poly(p-benzamide)(I) and Poly(p-hydroxybenzoate)(II) have recently emerged commercially as high performance materials with unique properties, the first as the basis of high strength and high modulus fibres and the latter as an engineering plastic with excellent high temperature characteristics. In the course of work directed to the synthesis of the structurally related poly-(p-benzenesulphonamide)(III) and poly(p-benzenesulphonate)(IV) and their substituted derivatives we have looked for evidence for the intermediacy of the sulphenes (V) and (VI) respectively:

The role of glass in chemical analysis

The availability of various types of glass in the form of laboratory ware and the ease of fabrication of glass into special apparatus provides a valuable aid to the analytical chemist in many ways. Simple composition, good chemical durability and good thermal shock properties have made borosilicate glass a leader in general analytical applications. 96% silica glass has all the advantageous properties of borosilicate glass plus excellent thermal shock resistance and high service temperature characteristics. Other glasses, such as alkali resistant glass, low actinic glass, and aluminosilicate glass, are unique in their properties of good durability to alkaline solutions, absorption of ultraviolet light, and high service temperature respectively. Glasses with tailored optical transmittance or thermal expansions characteristics are useful in special applications. Progress in any field of science is dependent on the tools available for experimentation and glass, because of its versatility and flexibility, plays a vital role as an important laboratory implement for the analytical chemist.

Terratex

Terratex is a thin flexible inorganic insulation manufactured from asbestos fiber. Its excellent high-temperature characteristics promise to make it an ideal inexpensive class B insulation.

"terratex''-A thin flexible inorganic insulation

A limited number of inorganic insulations has been available to the designer, as compared with the variety of organic materials on the market today. The development of terratex, a thin, totally inorganic paper-like sheet, fills a gap in the inorganic insulation field. Laboratory tests and four years of service experience indicate that its excellent high-temperature characteristics and other properties may be utilized wherever it is advantageous to use inorganic insulation.