VEGETABLE OIL STRUCTURE AND ANTIOXIDANTS
Five vegetable oils: canola, soybean, corn, cottonseed and sunflower oils were characterized with respect to their composition by gas chromatography and viscosity. The compositions of the vegetable oils suggest that they exhibited substantially different propensity for oxidation following the order of: Canola < corn < cottonseed < sunflower ≈ soybean The effect of molecular structure of five different vegetables oils including: corn, soybean, canola, cottonseed and sunflower oils with no antioxidants added on the oxidative stability was calculated and the following order of oxidative stability would be expected: canola < corn < cottonseed < sunflower ≈ soybean. Soybean oil, which is one of the most commercially interesting of the vegetable oils in Brazil, was determined to be the most susceptible to oxidative degradation of those oils evaluated. Therefore, soybean oil was selected to be used for a study to evaluate the ability of an antioxidant to stabilize a vegetable oil relative to two commercially formulated petroleum quench oils: Micro Temp 157, a conventional oil, and Micro Temp 153B, a fast oil. The antioxidants selected for this study were Irganox L57 and Irganox L109. In addition, the potential for combinations of L57 and L109 to provide a synergistic improvement over either antioxidant individually was also examined. The results of this work showed following order of oxidative stabilization: L109 > L57 over 60 hours of accelerated testing. No synergism using a blend of L109 + L57 was observed with performance increasing with increasing amount of L109. As expected all of the antioxidant combinations evaluated were better than soybean oil with no antioxidant. However, none of the vegetable oils evaluated exhibited the oxidative stability obtained for either petroleum oil. Cooling curve analysis results were surprising since increasing viscosity observed for vegetable oils with deceasing stability did not exhibit any large effect on cooling rates or times. The reasons for this have not been definitively shown thus far.
A new quenching alternative
The quenching of ferrous alloys implies the controlled extraction of heat from a part at a rate sufficient to harden the part and still control the desired dimensional limitations. Quenchants in common use today are: molten metals, molten salts, petroleum oils, polymer solutions, water, and salt/water solutions. Each type of quenchant has its benefits and limitations. With current waste legislation and the trends toward environmentally friendlier industrial working fluids, many of these quenching products are coming under close scrutiny by the users and legislators. The most widely used quenchant is petroleum oil due to its favorable heat extraction characteristics. The dependence upon imports, price vulnerability, and contamination potential have caused suppliers and users to look into alternative products. Research into renewable resource, non-petroleum, vegetable oils has been going on globally for several years. The drawbacks encountered with many vegetable oils were widely known and only years of research enabled them to be overcome. The presently formulated product not only performs as well as petroleum oil but shows some characteristics better than those of the petroleum products, especially in the biodegradability and ecological aspects of the products. Stability and reproducible quenching properties have been proven with over two and one halfmore » years of field testing.« less
Spectroscopy of high rate events during active interrogation
Abstract Pulsed accelerators are being used for radiographic inspections in homeland security applications. Adding spectroscopic detection capability enables additional information to be extracted but challenges signal processing hardware. This work compares two approaches to cost-effective digital spectroscopy systems designed to handle these high rate scenarios. In the first system, the signal from a PMT is directly digitized and then deconvolved on a PC using standard techniques. Bypassing the preamplifier, this system can handle high count rates (>10 6  cps) from an LaCl 3 detector with no dead time and an energy resolution of 5% at 1.33 MeV. Spectra acquired from fission product gamma rays between interrogation pulses are shown. At higher rates, this approach is limited by the DAQ transfer rate to the PC. Instead, we tested a fast ADC (125 MSPS) and an FPGA that performed onboard, real-time digital signal processing (DSP). The energy spectrum is generated on the FPGA board during the measurement and transferred later. This system was tested in nuclear resonance fluorescence (NRF) experiments. Resonance peaks from NRF reactions are shown.