http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Powder Metallurgy for Light Weight and Ultra-Light Weight Materials
Kieback, B.,Stephani, G.,Weiβgarber, T.,Schubert, T.,Waag, U.,Bohm, A.,Anderson, O.,Gohler, H.,Reinfried, M. The Korean Powder Metallurgy Institute 2003 한국분말재료학회지 (KPMI) Vol.10 No.6
As in other areas of materials technology, the tendency towards light weight constructions becomes more and more important also for powder metallurgy. The development is mainly driven by the automotive industry looking for mass reduction of vehicles as a major factor for fuel economy. Powder metallurgy has to offer a number of interesting areas including the development of sintered materials of light metals. PM aluminium alloys with improved properties are on the way to replace ferrous pars. For high temperature applications in the engine, titanium aluminide based materials offer a great potential, e.g. for exhaust valves. The PM route using elemental powders and reactions sintering is considered to be a cost effective way for net shape parts production. Furthermore it is expected that lower costs for titanium raw materials coming from metallurgical activities will offer new chances for sintered parts with titanium alloys. The field of cellular metals expands with the hollow sphere technique, that can provide materials of many metals and alloys with a great flexibility in structure modifications. These structures are expected to be used in improving the safety (crash absoption) and noise reduction in cars in the near future and offer great potential for many other applications.
Synthesis of Intermetallics and Nanocomposites by High-Energy Milling
Bernd F. Kieback,H. Kubsch,Alexander Bohm,M. Zumdick,Thomas Weissgaerber The Korean Powder Metallurgy Institute 2002 한국분말재료학회지 (KPMI) Vol.9 No.6
Elemental powders are used in high energy milling processes for the synthesis of new compounds. The low temperature solid state reactions during milling in inert gas atmosphere may result in intermetallic phases, carbides, nitrides or silicides with a nanocrystalline structure. To obtain dense materials from the powders a pressure assisted densification is necessary. On the other side the defect-rich microstructure can be used for activated sintering of elemental powder mixtures to obtain dense bodies by pressureless sintering. Results are discussed for nanocrystalline cermet systems and for the sintering of aluminides and silicides.
Nanodispersion-Strengthened Metallic Materials
Weissgaerber, Thomas,Sauer, Christa,Kieback, Bernd The Korean Powder Metallurgy Institute 2002 한국분말재료학회지 (KPMI) Vol.9 No.6
Dispersions of non-soluble ceramic particles in a metallic matrix can enhance the strength and heat resistance of materials. With the advent of mechanical alloying it became possible to put the theoretical concept into practice by incorporating very fine particles in a flirty uniform distribution into often oxidation- and corrosion- resistant metal matrices. e.g. superalloys. The present paper will give an overview about the mechanical alloying technique as a dry, high energy ball milling process for producing composite metal powders with a fine controlled microstructure. The common way is milling of a mixture of metallic and nonmetallic powders (e.g. oxides. carbides, nitrides, borides) in a high energy ball mill. The heavy mechanical deformation during milling causes also fracture of the ceramic particles to be distributed homogeneously by further milling. The mechanisms of the process are described. To obtain a homogeneous distribution of nano-sized dispersoids in a more ductile matrix (e.g. aluminium-or copper based alloys) a reaction milling is suitable. Dispersoid can be formed in a solid state reaction by introducing materials that react with the matrix either during milling or during a subsequent heat treatment. The pre-conditions for obtaining high quality materials, which require a homogeneous distribution of small dis-persoids, are: milling behaviour of the ductile phase (Al, Cu) will be improved by the additives (e.g. graphite), homogeneous introduction of the additives into the granules is possible and the additive reacts with the matrix or an alloying element to form hard particles that are inert with respect to the matrix also at elevated temperatures. The mechanism of the in-situ formation of dispersoids is described using copper-based alloys as an example. A comparison between the in-situ formation of dispersoids (TiC) in the copper matrix and the milling of Cu-TiC mixtures is given with respect to the microstructure and properties, obtained.
Handtrack Dirk,Sauer Christa,Kieback Bernd 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Ultra-fine grained and dispersion-strengthened titanium materials (Ti-Si, Ti-C, Ti-Si-C) have been produced by high energy ball milling and spark plasma sintering (SPS). Silicon or/and carbon were milled together with the titanium powder to form nanometer-sized and homogeneously distributed titanium silicides or/and carbides as dispersoids, that should prevent grain coarsening during the SPS compaction and contribute to strengthening of the material. The microstructures and the mechanical properties showed that strength, hardness and wear resistance of the sintered materials have been significantly improved by the mechanisms of grain refinement and dispersion strengthening. The use of an organic fluid as carrier of the dispersoid forming elements caused a significant increase in ductility.
p53 유전자가 삽입된 재조합 아데노 바이러스와 항암 화학요법제에 의한 난소암 세포주의 시험관내 성장억제
김태응,김용욱,김흥기,노덕영,김진우,정재근,Kieback, Dirk G.,남궁성은 대한부인종양 콜포스코피학회 2001 Journal of Gynecologic Oncology Vol.12 No.1
Objective: In an effort to develop a more effective therapeutic strategy for ovarian cancer, we examined whether the restoration of the wild-type p53 gene can enhance the therapeutic effect of chemotherapy. Methods: In this study, Ov-ca-2774 cells, which are known to have p53 point mutation and cisplatin-resistance, were selected and currently used chemotherapeutic agents including cisplatin, carboplatin, paclitaxel, etoposide, topotecan, and doxorubicin were added concurrently or sequentially with adenovirus-mediated p53 gene transfer (Ad5CMV-p53). Results: Transfer of the wild-type p53 cDNA gene into Ov-ca-2774 cells showed 55% cell killing in vitro at a multiplicity of infection (MOI) of 40. Although the combination of carboplatin or paclitaxel followed by p53 gene transfer with an interval of 48 h manifested no enhanced cell killing compared with cells infected with Ad5CMV-p53 alone, the other combinations of chemotherapeutic agents and p53 gene transfer resulted in 15% to 37% further cell killing (P$lt;0.05). Furthermore, p53 gene transfer followed by doxorubicin with an interval of 24 h and concurrent combination of etoposide with p53 gene transfer showed significant difference in cell killing in contrast to the other combination strategies in the respective chemotherapeutic agent exposure groups (P$lt;0.05). Conclusion: Our data demonstrated that combination of p53 gene transfer and chemotherapeutic agents had higher cell killing than either of these two modality alone.
Analysis of Particle Rearrangement during Sintering by Micro Focus Computed Tomography (μCT)
Nothe M.,Schulze M.,Grupp R.,Kieback B.,Haibel A.,Banhart J. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
The decrease of the distance between particle centers due to the growth of the sinter necks can be explained by the well known two-particle model. Unfortunately this model fails to provide a comprehensive description of the processes for 3D specimens. Furthermore, there is a significant discrepancy between the calculated and the measured shrinkage because particle rearrangements are not considered. Only the recently developed analysis of the particle movements inside of 3D specimens using micro focus computed tomography (μCT), combined with photogrammetric image analysis, can deliver the necessary experimental data to improve existing sintering theories. In this work, μCT analysis was applied to spherical copper powders. Based on photogrammetric image analysis, it is possible to determine the positions of all particle centers for tracking the particles over the entire sintering process and to follow the formation and breaking of the particle bonds. In this paper, we present an in-depth analysis of the obtaine data. In the future, high resolution synchrotron radiation tomography will be utilized to obtain in-situ data and images of higher resolution.
고상공정에 의해 제조된 AIN-Cu 나노복합재료의 조직 특성과 열팽창계수 측정에 관한 연구
Lee, Gwang-Min,Lee, Ji-Seong,Lee, Seung-Ik,Kim, Ji-Sun,Weissgaerber, T.,Kieback, B. 한국재료학회 2001 한국재료학회지 Vol.11 No.10
The present study was carried out to investigate the effect of MA processing variables on the microstructural properties of composite powders and the coefficient of thermal expansion of pulse electric current sintered AlN-Cu powder compacts. The AlN-Cu powders had a size of less than 15 $\mu\textrm{m}$ with 25 nm size of copper crystallite after MA 32 hours. The finely distributed AlN-Cu powder compacts were completely achieved after PECS. The residual oxygen was considerably removed after hydrogen reduction treatment. The residual carbon was completely removed to 97%. The CTE of AlN-Cu powder compacts showed a good consistency with Kingery-Tuner model when the volume fraction of copper was less than 60%. When it was more than 60%, the CTE had a good agreement with Series model.