PM Material Research Articles

Spray Forming of Magnesium Alloys and Composites

Rapid solidification can play an important role in the development of high performance magnesium alloys and composites. The investigation reported concentrate don spray forming of magnesium alloys which are difficult to cast, i.e. those with a high content of intermetallic phases, e.g. with rare earths, aluminium, or calcium. The process parameters were found to exert a considerable influence on the microstructure and properties of particle reinforced magnesium matrix composites. The examined composites consisted of commercial QE22 alloy with small silicon carbide particles (8–12 μm) as reinforcement. After spray forming the alloys were extruded followed by characterization of the resulting microstructure and determination of mechanical properties. The results are discussed for the various systems investigated and compared with those for extruded PM material. PM/0755

Analysis of gas atomized novel copper alloys: R.G. Iacocca, R.M. German. (Pennsylvania State University, Pennsylvania, USA)

Automotive steering columns use a variety of levers to lock the tilt mechanism in position. A PM material has been developed to withstand the impact and hardness performance requirements of this application. The part only requires honing of the pivot hole to meet the specified tolerance. Long term plans are to achieve the performance requirements using a modified version of the material. This has a higher graphite addition and can be used after tempering the ‘as-sintered’ product, say Brian James and Thomas Murphy of Hoeganaes Corp Riverton, Riverton, New Jersey, USA, and Vernon Potter of Presmet Corp, Worcester, Massachusetts, USA.

A NEW DOUBLY SALIENT PERMANENT MAGNET MOTOR FOR ADJUSTABLE SPEED DRIVES

ABSTRACT A new type of doubly salient motor is presented in this paper in which the field excitation is provided by permanent magnets. This doubly salient Permanent Magnet (DSPM) motor is shown to be kindred to square waveform permanet magnet brushless dc (PM-BLDC) motors in principle. However, they are different from the latter in that they are capable of a considerable constant power range when properly designed. Finite Element Analysis and Transient Simulation studies are utilized to investigate the characteristics of this new type of PM motor. A prototype DSPM motor is designed and comparison is made between this new type of motor and other types of motor on the basis of performance of the entire drive. By fully exploiting the merits of modern high energy PM material and the doubly salient structure, the DSPM motor can offer higher performance expectation over many existing motors in terms of efficiency, torque density, torque-to-current ratio, torque-to-inertia ratio etc. with a relatively simple str...

Lead gives PM material high lubricity

Lead gives PM material high lubricity

Steering column tilt lever — PM material development

Automotive steering columns use a variety of levers to lock the tilt mechanism in position. A PM material has been developed to withstand the impact and hardness performance requirements of this application. The part only requires honing of the pivot hole to meet the specified tolerance. Long term plans are to achieve the performance requirements using a modified version of the material. This has a higher graphite addition and can be used after tempering the ‘as-sintered’ product, say Brian James and Thomas Murphy of Hoeganaes Corp Riverton, Riverton, New Jersey, USA, and Vernon Potter of Presmet Corp, Worcester, Massachusetts, USA.

Characterization of cellular and extracellular plasmamembrane vesicles from a low metastatic lymphoma (Eb) and its high metastatic variant (ESb): inhibitory capacity in cell-cell interaction systems

Spontaneously shed extracellular plasma membrane vesicles (ECM) of a highly metastatic murine tumor line (ESb) were compared (i) with plasma membrane vesicles (PM) of the same cells prepared by the nitrogen cavitation method and (ii) with ECM and PM preparations of the related low metastatic tumor line Eb. From a previous biochemical analysis it was concluded that the exfoliation of ECM vesicles, which is very pronounced in metastatic ESb cells, is not a random process. This conclusion is further corroborated by the present functional analysis. Compared to ESb PM, ESb-derived ECM were selectively enriched for Fc receptors and depleted in glycoproteins with affinity for hepatocytes. Tumor-derived ECM carried the same tumor antigen as the corresponding tumor line and showed in comparison to PM material an increased inhibitor capacity in a T-cell-mediated tumor-specific cytotoxicity test.

A 4 KMC satellite TWT for the AT&T communication satellite

This TWT was especially developed for the service in a satellite repeater. The application necessitated heavy emphasis on high efficiency, long life, reliability, and ruggedness for launch. An overall efficiency of 31% is achieved with an electronic efficiency which exceeds 36% and a ruggedized heater that requires about 1.5 watts. The collector is depressed to less than half the helix voltage. The tube is designed for a life in excess of 10 years and every precaution is taken to make it extremely reliable. The focusing structure is a Single Reversal Magnet. This new method reduces the weight of the PM material by more than a factor of four over a straight field magnet, yet it retains its excellence of focusing. Although it is heavier than the PPM circuit, it requires much fewer critical machined parts. Beam transmission of better than 99% have been measured with full power output.