Thermal stability of hafnium silicate dielectric films deposited by a dual source liquid injection MOCVD

The hafnium and silicon precursors, Hf(NMe₂)₄ and Bu^tMe₂SiOH, have been investigated for the MOCVD of high-κ hafnium silicate, (HfO₂)_1–x –(SiO₂) _x films for gate dielectric applications. Control of the silica concentration in the hafnium silicate can be achieved by varying the relative precursor ratios up to a saturation level of 35–40% SiO₂. The thermal stability of the resulting hafnium silicate films in air has been investigated using medium energy ion scattering. Internal oxidation of the underlying silicon substrate is discernable when the films are annealed in dry air for 15 min over the temperature range 800–1000 °C.     

Comparison of the wear resistance of various grades of cemented carbides that may find application in wood machining

A laboratory test is described in which specimens of rectangular cemented carbide tool inserts of a standard size are allowed to slide against a rapidly rotating fiberboard disc in either the presence or the absence of a mist spray of a dilute organic acid (tannic acid or acetic acid) to simulate the cutting of green wood and cured wood respectively. It is shown that the worn surfaces of cemented carbide tools used in (field) service are remarkably similar to the worn surfaces of specimens used in the laboratory (simulation) tests.Extensive results are presented that show quantitatively the progressive wear of a wide range of cemented carbides as a function of time for sliding under wet and dry conditions. It is shown that wear depends on the type and amount of binder present in the cemented carbide and on the nature of the environment. Materials with Co-Cr and Ni-Cr binders containing significant amounts of chromium showed the greatest resistance to wear.     

Surface damage during machining of annealed 18% nickel maraging steel Part 1 — Unlubricated conditions

The effect of cutting speed and tool wear land length on the surface damage produced during the machining of annealed 18% nickel maraging steel under dry orthogonal conditions was determined. Machined test pieces were examined with a scanning electron microscope and an optical microscope. Surface roughness was determined with a profilometer.The results of the investigation show that during machining a wide variety of different forms of surface damage is generated. The machined surfaces show extended regions where both coarse and fine scale surface damage have occurred at cutting speeds up to 0.1 m s^?1, whereas at cutting speeds greater than 0.1 m s^?1 the surfaces show evidence only of fine scale surface damage. It is suggested that the regions of coarse scale surface damage are associated with the phenomenon of partially discontinuous chip formation and the nucleation of cracks in the vicinity of the tool nose region. Several mechanisms of crack nucleation and propagation, which are thought to account for the occurrence of many aspects of the surface topography observed, are presented and discussed. It is suggested also that the regions of fine scale surface damage are associated with the phenomenon of continuous chip formation and interaction between the tool nose region and the freshly machined workpiece surface.It is shown that scanning electron microscopy is more indicative of the true condition of the surface than surface roughness measurements.     

The role of tool composition and tool geometry in controlling the surface finish in machining wood

An examination of several brazed cemented carbide tool inserts that were used in service for cutting cured (dry) pine is described. A laboratory test is also described where the relative resistance to chipping of the brazed tool inserts was measured.It is shown that tool wear occurs through a continuous increase in the tool cutting edge radius that produces a deterioration in the appearance of the machined surface. It is also shown that an increase in either the binder volume fraction or the tool wedge angle produces an increase in the energy absorbed on impact. It is suggested that if progressive wear determines the useful life of a cemented carbide cutting tool then a low volume fraction of binder is required whereas if tool edge chipping determines the useful life of a cutting tool then a large volume fraction of binder and a large tool wedge angle are required.     

Kilopixel X-ray Microcalorimeter Arrays for Astrophysics: Device Performance and Uniformity

We are developing kilopixel arrays of TES microcalorimeters to enable high-resolution x-ray imaging spectrometers for future x-ray observatories and laboratory astrophysics experiments. Our current array design was targeted as a prototype for the X-ray Microcalorimeter Spectrometer proposed for the International X-ray Observatory, which calls for a 40×40-pixel core array of 300?μm devices with 2.5?eV energy resolution (at 6?keV). Here we present device characterization of our 32×32 arrays, including x-ray spectral performance of individual pixels within the array. We present our results in light of the understanding that our Mo/Au TESs act as weak superconducting links, causing the TES critical current (I _c ) and transition shape to oscillate with applied magnetic field (B). We show I _c (B) measurements and discuss the uniformity of these measurements across the array, as well as implications regarding the uniformity of device noise and response. In addition, we are working to reduce pixel-to-pixel electrical and thermal crosstalk; we present recent test results from an array that has microstrip wiring and an angle-evaporated copper backside heatsinking layer, which provides copper coverage on the four sidewalls of the silicon wells beneath each pixel.     

New Ways of Granular Activated Carbon Application in the Corn Sweetener Purification

Adsorption on granular activated carbon is a well established means of decolorising corn sweeteners. The handling and reactivation of the activated carbon has a major impact on the performance and operating cost of the system. As an indication, investment and operating costs are compared for granular and powdered carbon. Then a new approach, aiming specifically at more flexibility and a better operating and cost control of the granular carbon handling and reactivation is presented.