Advanced Materials Research Vols. 490-495

Abstract: With the development of automotive industry, new high strength and high performance steel sheets are used more and more widely, which are the basis of weight reduction and safety improvement for automobiles. Taking examples of the design of car body, this paper focused on the remarkable effects of the application of AHSS in automobile lightweight, car safety and environment. It was also pointed out that the key topics will fall in the forming technique of AHSS and the applications of AHSS to new car body design to enhance automobile safety.

Abstract: As an emerging brand new type of engineering material for a variety of important high technology applications, the deep understanding of the mechanical behavior of freestanding diamond films has become an emergent task of vital importance. Of the many deposition methods dc arc plasma jet has been regarded as the most promising technique for large area high quality and low cost production of freestanding diamond films. In the present paper, recent progress in mechanical properties of freestanding diamond films mainly by high power dc arc plasma jet with rotating arc root and gas recycling is reviewed. Testing methods for fracture strength and fracture toughness are discussed. Experimental data are presented and compared to that by MWCVD. Dc arcjet diamond films start to oxidize at about 700°C, however, oxidation up to 800°C for 10 min does not affect the fracture strength. Fracture mechanism is discussed. The strange mechanical behavior of freestanding diamond films is explained. It is surprising that CVD diamond film is such a kind of material which is strong, but full of different size of defects. It is hoped that the present paper will be helpful for those who wish to understand and use this brand new type of engineering material.

Abstract: Many control systems are subject to extraneous disturbance signals that cause the system to provide an inaccurate output. The extraneous disturbance signals in steel rolling process are analysis in this paper. If the frequency spectrums of the noise and input signals are of a different character, the output signal-noise ratio can be maximized, often by simply designing a closed-loop system transfer function that has a low-pass frequency response.

Abstract: Alumina/Al-Si alloy composites were manufactured by squeeze casting. The morphology of eutectic Si in the composite was observed on scanning electronic microscope, and the modified mechanism of the eutectic Si in the composite was approached. The alumina fiber in the composite could trigger twin during the growth of Al-Si eutectic and lead to modification of the eutectic Si near the fiber.

Abstract: In order to solve the drying problems in the deep-processing of pepper, peppers were dried through blanching pre-treatment and hot-air drying process. Orthogonal test designs were carried out to investigate factors influencing the quality and moisture content of pepper. The results showed that the whole drying process was a reduction speed drying, hot-air temperature and wind speed have significantly affected on the drying rate of pepper, but the impact of hot-air temperature was more prominent than wind speed; hot-air temperature was found to be the primary parameter to affect the quality of the pepper, wind speed was the secondary one and followed by packing thickness; drying time was found to be the primary parameter to affect the moisture content of the pepper in the drying process, the best drying conditions were as follows: wind temperature was 80°C, wind speed was 10 m/s, packing thickness was 80 cm, drying time was 12 h after 100°C steam blanching pre-treatment

Abstract: The rheological stress behavior and microstructure change of high silicon nickel-copper alloy NCu30-4-2-1 during high-temperature compression were studied with a Gleeble-1500 thermal simulation tester. Based on the results, extrusion tests were carried out and a suitable extrusion temperature and extrusion rate range were determined. At these extrusion parameters, the success rate can be significantly improved; in addition, the extrusion bars have superior properties, such as superior strength, hardness, wearing resistance, high-temperature resistance, corrosion resistance, bonding resistance, dimensional stability and machinability.

Abstract: The CrN films and CrBN films were successfully deposited by medium frequency magnetron sputtering in a mixture gas of nitrogen and argon. X-ray diffraction analysis shows that the CrN have preferential orientation of (111), (200) and (222). And the patterns of CrBN films is similar to that of CrN. The CrN films have smooth surfaces with dense and continuous microstructure and the CrBN films have glassy packed structure without columnar grains. The hardness of CrBN films were remarkable improved because of B attending.

Abstract: A research on the effect of strip defect in the notched specimen of low alloy hot rolled steel 16MnR at -196°C is carried out in this paper. 4-point positive and negative bending experiments of notched specimen with different preloads are carried out to introduce strip defects of different dimensions in the front of notch. And then the residual stress and work hardening is eliminated through high temperature tempering. Bending fracture experiment is carried out at -196°C. Through microscopic observation and the measurement and analysis of mechanical parameters, it is discovered that: when the preload ratio P0/Pgy0.861, the Pf /Pgy rapidly decreases as the P0/Pgy increases. That’s because the increase of local high stress-strain region caused by the strip defect at the front notch end makes the distribution of crack-shaped nucleus active region of cleavage fracture increase, causes the cleavage initiation and leads to discrete numeric values of material notch toughness Pf and W.

Abstract: Homoepitaxial diamond layers were grown on commercial 3.5 x 3.5 x 1.2 mm3 HPHT synthetic type Ib (100) single crystal diamond plates using a DC Arc Plasma Jet CVD operating at gas recycling mode. The effects of substrate temperature and CH4/H2 ratio on the surface morphology, the growth rate and the quality of the synthesized diamond have been studied using optical microscopy and Raman spectroscopy. With no intentional nitrogen added, the growth rate up to 12.3µm/h has been obtained in the single crystal diamond sample deposited at 1000 °C with CH4/H2=0.625%, exhibiting relatively smooth surface morphology without any growth hillocks nor non-epitaxial crystallites, and presenting the typical feature of the epitaxial step-flow growth. The full width at half maximum (FWHM) of the Raman spectra was 2.08 cm-1, which was close to that of the natural type IIa single crystal diamond.

Abstract: To quantitatively detect the on-site test of the content of clenbuterol in pork, a photoelectric apparatus for the colloidal gold test to detect clenbuterol was developed based on green LED and linear CCD. This design method could realize a semi-quantitative analysis of clenbuterol concentrations ranging from 0 to 1 ng/ml. Such an apparatus could promote an integrated approach to the management of the community food safety