Partnerzy

Streszczenie:
This letter describes modelling and experimental results of low and high pressure shock waves (of the order of 100 and 1000 bar, respectively) induced by pulse laser radiation. Measurements were performed using piezoelectric polymer PVDF sensors. The results of numerical calculations and their comparison with an experiment have been posted. Measured and calculated results have been used in estimation of the temporary course of signals from a fibre VISAR interferometer which measured the movement velocity of a steel plate driven by the analysed shock waves. The description is supplemented with the results of magnitude measurements of surface plastic deformation and material microstructure of samples.

Streszczenie:
In this work alumina preforms with an open porosity of 85 and 90% were produced by the replication method. The obtained preforms were used for the fabrication of Cu–Al2O3 composites. We analyzed the effect of applying pressure during a hot-pressing process on the microstructure and mechanical and thermal properties of the obtained materials. It was found that application of higher pressure (10 MPa) during sintering led to the destruction of the ceramic preforms. It facilitated filling of the remaining pores with copper, which resulted in a more homogeneous material with better mechanical and thermal properties.

Słowa kluczowe:
Cu–Al2O3 composites, hot-pressing process, ceramic reforms, microstructure, mechanical properties

Streszczenie:
This paper presents new solution to manufacturing Cu-Al2O3 composites with a dispersed reinforcement phase. It consists in substituting commonly used commercial alumina powder with crushed ceramic foam. Very low strength of thin-walled Al2O3 porous foams results in both their easy destruction and isolation of fragments <200 μm. The addition of the ceramic phase is 3-10 vol.%. The sintering process is performed for 30 min in a hot-press at 1050°C and 30 MPa. The aim of the presented paper is to study the effect of the volume content of the ceramic phase on the microstructure and selected physical and thermal properties of copper - alumina composites.

Słowa kluczowe:
ceramic preform, composite, copper, sintering

Streszczenie:
Alumina/copper composites have been used where high thermal conductivity, high absorption and dissipation of heat, high resistance to thermal fatigue and good frictional wear resistance are required. This kind of composites may be applied in medicine, electronic and automotive industry. Both the physical and mechanical properties of this type of composites are strongly influenced by the properties of its individual constituents and, also, by the properties of interface layer between ceramic and metal. One of the solution, from the point of view of the best properties’ achievements (especially thermal, structural and shape stability), is the production of ceramic-metal composites with interpenetrating networks structure. They can be produced using porous alumina performs, which are infiltrated (pressure or pressureless) by molten metal or sintered with metallic powders. The subject of the presented paper is the development of the interpenetrating network Al2O3-Cu composites, processed by sintering porous ceramic perform (85 and 90% porosity) with copper powder. The paper presents the new developed technology, results of microstructure investigations, measurements of the selected physical and mechanical properties and the analysis of the influence of the processing conditions on the properties and interface morphology between ceramic and copper