Milivoj Konstantin Brun
General Electric
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Publication
Featured researches published by Milivoj Konstantin Brun.
Acta Metallurgica Et Materialia | 1995
Sang Chul Han; Duk Yong Yoon; Milivoj Konstantin Brun
Abstract When alumina polycrystal is heat-treated at 1400 and 1500°C with Al2O3-Cr2O3 powder mixtures, the grain boundaries migrate, forming behind them a solid solution enriched with Cr2O3. The migration rate increases with the heat-treatment temperature and the Cr2O3 content in the mixture. The driving force for the migration is believed to raise from the coherency strain in the Cr2O3 diffusion zone in front of the migrating grain boundaries. The migrating grain boundaries develop strong faceting with flat segments meeting at sharp edges. Because of the elastic anisotropy of alumina, the diffusional coherency strain energy Gc(n) varies with the surface orientation n of the retreating grain, but the variation is smooth at the minimum in the polar plot of Gc(n). Therefore, smoothly curved boundaries meeting at sharp edges are predicted for the growth shape contrary to the observed flat facet boundaries. It is suggested that the grain boundary mobility may vary with the grain surface orientation and therefore influence the growth shape.
ASME Turbo Expo 2001: Power for Land, Sea, and Air | 2001
Gregory Scot Corman; Anthony John Dean; Stephen Brabetz; Keith Robert McManus; Milivoj Konstantin Brun; Peter Joel Meschter; Krishan Lal Luthra; Hongyu Wang; Robert Michael Orenstein; Mark Stewart Schroder; Devin Martin; Roberta De Stefano; Leonardo Tognarelli
GE is continuing work on the development of Melt-Infiltrated Ceramic Matrix Composites (MI-CMC) for use in industrial gas turbine engine components. Long-term environmental degradation of test samples under realistic engine conditions is being determined using a unique high-pressure combustion rig apparatus. Rig testing is also being used to evaluate an F-class 1st stage shroud system incorporating an MI-CMC inner shroud component. While large, advanced engines, such as the F and H classes, offer the greatest benefits for using MI-CMC components, initial engine tests have been done using a GE-2 (2MW) machine to reduce costs and risk. Long term (1000 hours) engine testing results for single piece GE-2 shrouds are also described.Copyright
International Journal of Refractory Metals & Hard Materials | 1992
Milivoj Konstantin Brun; Minyoung Lee
Abstract A number of brittle-brittle composites have been synthesized by reactive hot pressing. By using one inert phase and a phase formed in situ from metal hydride and a solid nonmetal, it was possible to produce microcomposites in which the reacting phase formed a continuous matrix, and isolated the grains of the inert phase. Densification rates for the reactively hot-pressed materials were appreciably higher than for the conventionally hot-pressed materials with the same nominal composition. Composites formed by Al2O3TiC, Al2O3TiB2 and B4CTiB2 exhibited high Rockwell A hardness. Reactively hot-pressed Al2O3TiC composite was tested on inconel 718 and exhibited performance better or equivalent to the commercially available Al2O3TiC tool. B4CTiB2 tested on titanium 6–4 alloy exhibited higher uniform flank wear at short cutting times than a commercial WC 6% Co cutting tool (Carboloy grade 883). However, it continued cutting to the end of the 3-min test, while the carbide tool was limited to 2 min of cutting due to gross deformation. The volume of the tool material worn showed linear dependence on cutting times at all cutting speeds higher than 200 surface feet per minute (sfm). At those speeds, the dominant wear mechanism appeared to be chemical interaction with the workpiece, while at 200 sfm, microfracturing became more prominent.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 1988
Minyoung Lee; Milivoj Konstantin Brun
Abstract The microindentation and the three-point bend test of the chevron-notched-bar methods were used to measure the fracture toughness of several common ceramic materials between room temperature and 1000 °C. The fracture toughness calculated from the maximum loads of chevron-notched beams was shown to be in good agreement with the values given in the literature. Agreement of the results obtained by the two methods was excellent at room temperature. The two methods, however, gave opposite trends for the fracture toughness of silicon nitride as a function of temperature. Because of the fewer assumptions involved in the chevron-notched-beam method, it is considered preferable despite more complicated specimen preparation.
ASME Turbo Expo 2000: Power for Land, Sea, and Air | 2000
Gregory Scot Corman; Anthony John Dean; Stephen Brabetz; Milivoj Konstantin Brun; Krishan Lal Luthra; Leonardo Tognarelli; Mario Pecchioli
GE has developed SiC fiber reinforced SiC-Si matrix composites produced by silicon melt infiltration (MI) for use in gas turbine engine applications. High temperature, high pressure combustion rig testing and engine testing has been performed on combustor liners and turbine shrouds made from such MI composites. Frame 5 sized combustor liners were rig tested under LHE diffusion flame conditions for 150 hours, including 20 thermal trip cycles, with no observed damage to the ceramic liners. Similarly, 46 cm diameter, single piece turbine shroud rings were fabricated and tested in a PGT-2 gas turbine engine. The fabrication and testing of both components are described.Copyright
Advanced Ceramic Materials | 1988
Raj N. Singh; Milivoj Konstantin Brun
Archive | 2006
Ming Feng Hsu; Kripa Kiran Varanasi; Nitin Bhate; Gregory Allen O'neil; Judith Stein; Tao Deng; Shannon Maile Okuyama; Norman Arnold Turnquist; Milivoj Konstantin Brun; Farshad Ghasripoor; Kasiraman Krishnan; Christopher Fred Keimel
Advanced Ceramic Materials | 1988
Milivoj Konstantin Brun; Raj N. Singh
Archive | 1989
Charles David Greskovich; William Paul Minnear; Milivoj Konstantin Brun; Robert Joseph Riedner
American Ceramic Society Bulletin | 1993
K. L. Luthra; Raj N. Singh; Milivoj Konstantin Brun