Microwave joining

There are several claims in the literature regarding the maximum speed of microwave curing of epoxy adhesives. Claims have been made of ten- to twenty fold cure time reduction when compared to conventional thermal heating. A more practical estimate, however, is that microwave joining using epoxy-based adhesive will significantly reduce the curing time... 

Fig. 8 A scanning electron microscope micrograph of microwave-joined MaCor and hydroxyapatite, joined at 1020°C for 20 min in a single-mode 2.45 GHz microwave cavity. (MaCor is a mica-platelet reinforced glass ceramic and HAP is a bioceramic material.) (From Ref. f Reprinted with permission of The American Ceramic Society, www. ceramics.org. Copyright 2003. All rights reserved.)...

Beale GO, Arteaga FJ, Black WM (1992) Design and evaluation of a controller for the process of microwave joinning of ceramics. IEEE Trans Industr Electron 39 301-312... 

Wu, C. Y, and Benatar, A., Microwave Joining of HDPE Using Conductive Polymeric Composites, ANTEC Conf. Proc., Soc. Plastics Eng. 1992. 

Figure 38 Block diagram of microwave Joining apparatus. (After ref 81).

Palaith, D., Silberglitt, R. and Libe1o,E.L., Microwave Joining of ceramic materials. Presented at the 2nd International Conference on Ceramic Materials and Components for Engines, Lubeck-Travemunde, W. Germany. April 14-17, (1986). 

It is hoped that additional research groups will join in the development of microwave electrochemistry. 

Pure rotational spectroscopy in the microwave or far IR regions joins electron diffraction as one of the two principal methods for the accurate determination of structural parameters of molecules in the gas phase. The relative merits of the two techniques should therefore be summarised. Microwave spectroscopy usually requires sample partial pressures some two orders of magnitude greater than those needed for electron diffraction, which limits its applicability where substances of low volatility are under scrutiny. Compared with electron diffraction, microwave spectra yield fewer experimental parameters more parameters can be obtained by resort to isotopic substitution, because the replacement of, say, 160 by lsO will affect the rotational constants (unless the O atom is at the centre of the molecule, where the rotational axes coincide) without significantly changing the structural parameters. The microwave spectrum of a very complex molecule of low symmetry may defy complete analysis. But the microwave lines are much sharper than the peaks in the radial distribution function obtained by electron diffraction, so that for a fairly simple molecule whose structure can be determined completely, microwave spectroscopy yields more accurate parameters. Thus internuclear distances can often be measured with uncertainties of the order of 0.001 pm, compared with (at best) 0.1 pm with electron diffraction. If the sample is a mixture of gaseous species (perhaps two or more isomers in equilibrium), it may be possible to unravel the lines due to the different components in the microwave spectrum, but such resolution is more difficult to accomplish with electron diffraction. 

Joining another type of ancillary device to ICP-MS, Beary et al. developed a continuous-flow microwave digestion apparatus for isotope dilution analysis of lead in environmental samples [38]. Although introduction to the ICP torch was... 

Paulauskas, F. L., et al., Adhesive Bonding/Joining Via Exposure to Microwave Radiation, 27th International SAMPE Technical Conference, September 9-12, 1995. 

The microwave spectrum of CSFg observed by Kisliuk and Silvey (2 ) shows that the molecule is a symmetric rotor comprised of CFg and SFg groups joined by a C-S bond. The infrared ( i 4) and Raman (4) spectra obey the selection rules predicted for the point group We estimate all structural data except for the C-S bond length by analogy with the CF structure in CgFg... 

Fig. 7 A schematic of the time-temperature history of the processing cycle. Typically for conventional heating, the time at Thoid. the sintering or joining temperature, is in the order of 1 hr to several hours. For microwave processing, the time at temperature Thoid is 1020 min or less.

Successful ceramic/ceramic joints between both similar and dissimilar ceramic materials have been achieved both i) by layering materials in the green state, then firing,and ii) by joining fully dense materials (Fig. 8). In some instances, microwave... 

As is the case with ceramic sintering, joining, and powder synthesis, microwave-assisted fabrication of ceramic coatings can offer unique benefits. To expose the material surfaces for reaction with a gas phase, fibers or powder particles may be suspended by the flow of gas in the fluidized bed. In addition to the flow of the fluidizing gas, low frequency mechanical vibrations (for example, 10-15 Hz) may be applied to the container to reduce the tendency for the powders or fibers to sinter together to form clumps. As the powder size decreases, the powder s sinterability increases. While vibration may not be necessary for particles as large as, say, 50 pm, it may be beneficial for powder particles that are a few microns in diameter. 

Microwave sintering, joining, and thermal etching are three high-temperature processes for which there have been claims that microwave energy can densify, join, or etch at lower temperatures and/or shorter times than are required to produce the same results by conventional heating. Regardless of the presence... 

Aravindan, S. and Krishnamurthy, R., Joining of ceramic composites by microwave heating, Mater. Letters 38 (1999) 245-249. 

In September 2007, following my nomination as a university lecturer at the University of Strasbourg, I joined the laboratory of Dr. Andre Mann in the faculty of pharmacy at Strasbourg. The recent work of this laboratory concerned the reaction of hydroformylation. They had just published an article on the synthesis of derivatives of kainic acid by cyclohydrocarbonylation (CHC) in collaboration with Professor Ojima, and another on olefin hydroa minomethylations assisted by microwave irradiation with Professor Taddei. One year before my arrival, a research student had the role of continuing... 

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