Metodyka pomiarów wielofunkcyjnych w monitorowaniu strefy skrawania z wykorzystaniem zjawisk dynamicznych w procesie toczenia nadstopów z zastosowaniem termowizji i szybkiego skanowania

Processes in a cutting zone are so complicated and dynamic, that their description is performed by specifically created models. As the models have faults and deviations, it is necessary to improve them so that these deviations become as little as possible or completely abolished and focus on the area of micro-cutting. Examining new ways should be based on the previous research and it is necessary to know the details of the contemporary knowledge. In examining the cutting zone one could widely use nondestructive methods (such as thermovision and high-speed scanning).Procesy zachodzące w strefie skrawania cechują się dużą dynamiką i złożonością. Stąd są najczęściej definiowane za pomocą specjalnie tworzonych modeli. Jednak same modele z reguły mają usterki i uproszczenia. Z tego względu więc niezbędna jest korekta modeli, dla zmniejszenia skali błędów lub ich całkowitego wyeliminowania. W trakcie poszukiwania nowych metod w opracowaniu modeli należy stosować współczesne możliwości badawcze strefy. Obecnie charakteryzacja strefy skrawania jest prowadzona za pomocą metod nieniszczących, m.in. termowizji i szybkiego skanowania

Structural development and properties of SiC-Si3N4 nano-microcomposites

The micro-nano structure of SiC-Si3N4 composite can be obtained by addition of amorphous Si-N-C powder,synthesized by pyrolysis of a mixture of polysilazanes to a starting mixture of conventional crystalline Si3N4 powder and sintering additives.The presence of SiC nano-inclusions a the grain boundaries hinders the Si3N4 grain grows, and the presence of SiC inclusions in the Si3N4 grains creates subgrain structures.The content of free carbon which is a consequense of the nonstoichiometry of the starting Si-N-C-powder, in the vicinity of the SiC-inclusions cancels the creation of subgrain stress boundaries

Mechanical properties of silicon nitride-based laminated ceramic composites

Translated from Slovak (Report of the Inst. of Materials Research, Slovak Academy of Science, Kosice, 1996)SIGLEAvailable from British Library Document Supply Centre-DSC:9023.190(VR-Trans--8229)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Functional ceramics via precursor chemistry coupled with forming methods

International audienc

In-situ carbon content adjustment in polysilazane derived amorphous SiCN bulk ceramics

The paper is concerned with in-situ carbon content adjustment in amorphous bulk silicon carbonitride ceramic matrices prepared by thermal polymer to ceramic conversion of crosslinked and compacted poly(hydridomethyl)silazane powders (NCP200). Heat treatment under inert (Ar) or reactive (Ar/NH3, NH3) atmosphere was applied for carbon content adjustment. Isothermal annealing steps at various intermediate temperatures were included into the schedule. Optimal annealing temperatures were found to be in the range from 500 - 550°C. Results are presented. Different possible chemical reactions are considered

SiC/Si3N4 nano/micro-composite - processing, RT and HT mechanical properties

Two SiC/Si3N4 nano/micro composites were prepared from a starting mixture of crystalline α-Si3N4, amorphous SiNC, Y2O3 and/or Al2O3. The composite material for room temperature (RT) application has high strength of 1200 MPa, Weibull modulus of 19 and moderate fracture toughness of 7 MPa m1/2. The composite for high temperature (HT) application, without Al2O3 has RT strength of 710 MPa and is able to keep 60% of its RT strength up to 1300°C. The creep resistance of composite material is approx. 1 order higher compared to relative monolith up to 1400°C

Investigation of the high temperature properties of structural ceramics Final report

The reported project aims at understanding the influence of the composition, microstructure, temperature, environment and loading condition on the high temperature deformation and fracture properties of different structural ceramics based on Si_3N_4 and Al_2O_3. The temperature dependence of Young's modulus of different Si_3N_4 based ceramics was studied using 4-point-bending tests in the temperature range from 25 to 1300 C. The experimental results of the subcritical crack growth in hot pressed Si_3N_4, Si_3N_4+Si_3N_4-whisker, Al_2O_3+SiC-whiskers and in situ reinforced Si_3N_4 systems show that in all cases a very intensive crack growth occurs at the temperature 1200 C, but its velocity for different material systems is different. In the case of the systems Si_3N_4, Si_3N_4+Si_3N_4-whisker, in-situ reinforced Si_3N_4 and Al_2O_3+SiC-whiskers the R-curve behaviour, i.e., the change of the crack growth resistance with rising crack extension at 1200 C was studied using static fatigue testing method. (orig.)Available from TIB Hannover: F95B1349+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Dense silicon carbide and silicon nitride-based ceramics with high electrical conductivity via precursor chemistry

International audienc