Thermal conductivity of nickel superalloy MAR-M247

The paper presents the narrow connection between γ’ phase dissolving and values of thermal conductivity. In annealing process the free space among γ’ particles (blocks) changes in certain cycle from fine to rough and back to fine. This is accompanied by decrease and subsequent increase of thermal conductivity as well as the sample density. The results of thermal conductivity coarse are supported by image analysis

Contribution to the thermal properties of selected steels

The paper deals with the influence of structural changes on heat transport phenomena of steels samples. Three samples of 10GN2MFA steel were thermally treated at quenching temperatures equal to 900 °C, 1 000 °C and 1 100 °C, and temperature of the tempering was 670 °C. Both thermal diffusivity and thermal conductivity increase with the quenching temperature. Specific heat capacity of steel samples after thermal treatment does not change significantly. Further three different high manganese steels were measured. Maximal content of Mn and C was 27 and 0,5 mass percent. From results of thermophysical properties after ageing, one can see the increase of thermal diffusivity up to 20 percent, thermal conductivity up to 15 percent, decrease of specific heat capacity is not significant. All measured values of thermophysical properties are in good agreement with literary data (before ageing)

Gass presure sintered Si₃N₄ – MgSiN₂ composites

Si₃N₄ and MgSiN₂-based ceramic composites have excellent thermo-physical and mechanical properties, however with limited industrial applications. In this paper the preparation of Si₃N₄/ MgSiN₂ composite by gas pressure sintering (GPS) is described and some of the mechanical properties like Vickers hardness and indentation fracture are characterised and compared with hot pressed (HP) samples. The 15,3 GPa hardness and 7,6 MPa∙m^1/2 fracture toughness of GPS composites was slightly lower compared to HP samples (16,5 GPa, 8 MPa∙m^1/2)

Thermal conductivity of nickel superalloy MAR-M247

The paper presents the narrow connection between γ’ phase dissolving and values of thermal conductivity. In annealing process the free space among γ’ particles (blocks) changes in certain cycle from fine to rough and back to fine. This is accompanied by decrease and subsequent increase of thermal conductivity as well as the sample density. The results of thermal conductivity coarse are supported by image analysis

Hydrogen Embrittlement of Welded Joint Made of Supermartensitic Stainless Steel in Environment Containing Sulfane

The work is focused on evaluation of resistance of the welded joint made of supermartensitic 13Cr6Ni2.5Mo stainless steel to sulfide stress cracking. Testing method A and solution B in accordance with NACE TM 0177 were used. All the testing samples were ruptured in a very short time interval but welded joint samples were fractured primarily in the weld metal or in heat affected zone and not in the basic material. Material analysis of samples were made with use of a ZEISS NEOPHOT 32 light microscope and a JEOL 6490LV scanning electron microscope

Overview of production of pre-preg, prototype and testing

The content of the scientific work is to evaluate the properties of matrix pre-preg systems of composite materials suitable for the production of high performance composite parts, for example for automotive or aerospace industry. The research work introduces composite materials, types, properties and fields of use of matrices and fibres. The main part deals with the description of the pre-preg production, the description of the state of the material conversion with a focus on the B-state of the resin, including the technologies for the production of composite materials from pre-preg systems. The practical part is focused on the testing of matrices intended for the manufacture of pre-preg systems of composite materials, it compares different types of epoxy matrix and glass fiber in several layers. The aim of the work is to evaluate the tested composite systems suitable for pre-preg applications, to compare the properties and parameters of the given application with the focus on the recommended production methods. The result of the work can then be used as the most suitable production application according to the customer's requirements for the product. © Published under licence by IOP Publishing Ltd.TBU in Zlin [IGA/FT/2018/004

Experimental method for complex thermo-mechanical material analysis

An experimental system for complex thermo-mechanical material analysis is presented in this article. The system provides simultaneous measurements of tensile properties as well as heat generation in the process of tensile deformation. The cooling curve of the sample after its reversible deformation was measured. On the basis of an exponential model of a cooling body with respect to the Biot number Bi, it is possible to calculate the specific heat capacity c p , the thermal diffusivity α, and the thermal conductivity k. The method had been tested on a variety of materials and the results were compared to those in the technical literature or obtained by reference independent experiments and showed very good agreement