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J. Wozniak, M. Kostecki, K. Broniszewski, W. Bochniak and A. Olszyna

Abstract

The main aim of this work was to study the effect of time and method of Al, SiC powders mixing on the microstructure and mechanical properties of composites. Moreover, the influence of applicating direct extrusion with a reversibly rotating die on the homogeneity of the composites was examined. Microstructure observations with the use of an optical microscope and scanning electron microscope were applied. A quantitative analysis of composite microstructure was conducted. The density (helium pycnometer method), Vickers hardness and the Young’s Modulus of the composites were also determined. The results show that the homogeneity of Al/SiC composites rises with an increase of mixing time. However, better results were obtained by application of high energy ball milling process.

Open access

Przemysław Korpas, Daniel Gryglewski, Wojciech Wojtasiak and Wojciech Gwarek

References Analog Devices Data. Hittite Data. Atmel Data. R. J. Trew, "SiC and GaN Transistors-is there Oe Winner for Microwave Power Applications?" Proceedings of the IEEE , vol. 90, pp. 1032-1047, June 2002. Sage Laboratories Inc. Raditek: Wireless, RF and Microwave Telecommunication Solutions. Cree. W. Wojtasiak and D. Gryglewski, "A 100 W SiC Mesfet

Open access

A. Strojny-Nędza, K. Pietrzak, M. Teodorczyk, M. Basista, W. Węglewski and M. Chmielewski

Abstract

This paper describes the process of obtaining Cu-SiC-Cu systems by way of spark plasma sintering. A monocrystalline form of silicon carbide (6H-SiC type) was applied in the experiment. Additionally, silicon carbide samples were covered with a layer of tungsten and molybdenum using chemical vapour deposition (CVD) technique. Microstructural examinations and thermal properties measurements were performed. A special attention was put to the metal-ceramic interface. During annealing at a high temperature, copper reacts with silicon carbide. To prevent the decomposition of silicon carbide two types of coating (tungsten and molybdenum) were applied. The effect of covering SiC with the aforementioned elements on the composite’s thermal conductivity was analyzed. Results were compared with the numerical modelling of heat transfer in Cu-SiC-Cu systems. Certain possible reasons behind differences in measurements and modelling results were discussed.

Open access

Jana Šic Žlabur, Sandra Voća, Nadica Dobričević, Mladen Brnčić, Filip Dujmić and Suzana Rimac Brnčić

, 420-424. Šic Žlabur J., Voća S., Dobričević N., Brnčić M., Dujmić F., and Karlović S., 2012. Possibilities of using high intensity ultrasound technology with stevia - a review. Croat. J. Food Technol. Biotechnol. Nutr. 7, 152-158. Tiwari B.K., O’Donnell C.P., Muthukumarappan K., and Cullen P.J., 2008. Effect of ultrasound processing on the quality and nutritional properties of fruit juices. Stewart Postharv. Rev., 4, 1-6. Zayova E., Stancheva I., Geneva M., Petrova M., and Dimitrova L., 2013. Antioxidant activity of in

Open access

S. Boczkal, A.J. Dolata and M. Nowak

The aim of the study was to describe the structure of composites based on the AlSi7Mg2Sr0.03 alloy matrix reinforced with SiC particles added in an amount of 10% and with a mixture of SiC and GR particles added in a total amount of 20%. Studies of the composite structure, were carried out by scanning electron microscopy (SEM). Based on the results of chemical analysis in microregions, an increased content of elements such as Mg, O and Si and of the precipitates was observed at the interface. In many places in the examined sample, GR particles formed partly disintegrated conglomerates with well developed boundaries. The effect of the content of particles of the reinforcing phase on the functional properties of the composite was investigated during studies of abrasion. The lowest mass loss of 5,33mg was obtained for the AlSi7Mg2Sr0.03 alloy reinforced with 10% SiC particles.

Open access

H. Rudianto, G.J. Jang, S.S. Yang, Y.J. Kim and I. Dlouhy

Abstract

Premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder was analyzed as matrix in this research. Gas atomized powder Al-9Si with 20% volume fraction of SiC particles was used as reinforcement and added into the alloy with varied concentration. Mix powders were compacted by dual action press with compaction pressure of 700 MPa. High volume fraction of SiC particles gave lower green density due to resistance of SiC particles to plastic deformation during compaction process and resulted voids between particles and this might reduce sinterability of this mix powder. Sintering was carried out under ultra high purity nitrogen gas from 565°-580°C for 1 hour. High content of premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder gave better sintering density and reached up to 98% relative. Void between particles, oxide layer on aluminum powder and lower wettability between matrix and reinforcement particles lead to uncompleted liquid phase sintering, and resulted on lower sintering density and mechanical properties on powder with high content of SiC particles. Mix powder with wt90% of Alumix 431D and wt10% of Al-9Si-vf20SiC powder gave higher tensile strength compare to another mix powder for 270 MPa. From chemical compositions, sintering precipitates might form after sintering such as MgZn2, CuAl2 and Mg2Si. X-ray diffraction, DSC-TGA, and SEM were used to characterize these materials.

Open access

A. Pasieka and Z. Konopka

Abstract

A method of pressure die casting of composites with AlSi11 alloy matrix reinforced with 20 vol. % of SiC particles and the analysis of the distribution of particles within the matrix are presented. The composite castings were produced at various values of the piston velocity in the second stage of injection, at diverse intensification pressure values, and various injection gate width values. The distribution of particles over the entire cross-section of the tensile specimen is shown. The index of distribution was determined on the basis of particle count in elementary measuring fields. The regression equation describing the change of the considered index was found as a function of the pressure die casting parameters. The conclusion presents an analysis of the obtained results and their interpretation.

Open access

Jana Šic Žlabur, Sandra Voća, Nadica Dobričević, Stjepan Pliestić, Ante Galić, Ana Boričević and Nataša Borić

., Hua S., Song H., and Xia C., 2014. Optimization of ultrasound-assisted extraction parameters of chlorophyll from Chlorella vulgaris residue after lipid separation using response surface methodology. J. Food Sci. Technol., 51, 2006-2013. Koubaa M., Roselló-Soto E., Šic Žlabur J., Režek Jambrak A., Brnčić M., Grimi N., Boussetta N., and Barba F.J., 2015. Current and new insights in the sustainable and green recovery of nutritionally valuable compounds from Stevia rebaudiana Bertoni. J. Agric. Food Chem., 63, 6835-6846. Kumcuoglu S., Yilmaz T., and

Open access

L. Weng, W. Han and Ch. Hong

Abstract

A HfB2 based ceramic matrix composite containing 20 vol.% SiC particles with 2 vol.% B4C as sintering additives was fabricated by hot-pressed sintering. The microstructure and properties, especially the thermal shock resistance of the composite were investigated. Results showed that the addition of B4C improved the powder sinterability and led to obtaining nearly full dense composite. The flexural strength and fracture toughness of the composite were 771 MPa and 7.06 MPam1/2, respectively. The thermal shock resistance tests indicated that the residual strength decreased significantly when the thermal shock temperature difference was higher than 600 °C. The large number of microcracks on the sample surface was the main reason for the catastrophic failure.

Open access

Damian Bisewski, Marcin Myśliwiec, Krzysztof Górecki, Ryszard Kisiel and Janusz Zarębski

References [1] Buttay, C., Raynaud, Ch., Morel, H. (2012). Thermal Stability of Silicon Carbide Power devices. IEEE Transactions on Electron Devices, 59(3), 761−769. [2] Buttay, C., Raynaud, Ch., Morel, H., Lazar, M., Civrac, G. (2011). High-Temperature Behavior of SiC Power Devices. Proc. of 14th European Conference on Power Electronics and Applications EPE2011, 1−9. [3] Kisiel, R., Guziewicz, M., Szczepański, Z., Król, K. (2010). An Overview of Materials and Bonding Techniques for Inner Connections in SiC High