MIKROSTRUKTURA A VLASTNOSTI NIKLU A JEHO NANOKOMPOZITU PŘIPRAVENÉHO ELEKTROLYTICKÝM POVLAKOVÁNÍM

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ELECTRODEPOSITED NICKEL AND ITS PARTICLE-REINFORCED NANOCOMPOSITE

článek v časopise - ostatní, Jost

čeština

Nanostrukturní čistý nikl a jeho nanokompozit byly připraveny elektrolytickým pokovováním na měděném substrátu za těchto podmínek:stejnosměrný proud 25mA, 30hod. Měděná podložka byla mechanicky odstraněna a tím byl získán experimentální materiál pro mechanické a creepové zkoušky. Předmětem studia bylo srovnání tahových a creepových vlastností elektrolyticky nanášeného čistého niklu a jeho kompozitu s nanometrickými částicemi SiO2. Creepové zkoušky byly provedeny v rozsahu teplot od 293K do 473K. Experimentální materiál (Ni a Ni+SiO2) byl studován pomocí REM a TEM. Studium bylo především zaměřeno na rozložení částic SiO2 v matrici a velikost zrn matrice i částic.

One major problem with research on the properties of the nanocrystalline materials is obtaining bulk fully densified material. The method which has been commonly employed to synthesize coating nanocrystalline materials is an electrodeposition. It is a simple, inexpensive and versatile method to produce dense metallic nanocrystals. Nanocrystalline pure nickel and its particle-reinforced nanocomposite were produced by electrodeposition onto copper substrate under these conditions: direct current, 25mA and 30h. After electroplating, the copper substrate was metallographically ground out to obtain free-standing samples for the mechanical and creep testing. The subject of study has been a comparison between the tensile properties and the creep characteristics of the electrodeposited nonreinforced nickel and its nanocomposite reinforced by nano-sized SiO2 particles at temperatures in the range from 293 to 473K. Specimens of the matrix phase (of pure Ni) and the composite were studied (in initial state and after static and creep deformation) using SEM and CTEM. The study was focused in particular on the size distribution of matrix phase grains and reinforcing particles. All the creep specimens were run to the final fracture. The results show that the creep resistance of the nickel nanocomposite reinforced by nano-sized SiO2 particles may be improved in comparison with the unreinforced nickel. Nanocomposite Ni-SiO2 exhibits better creep resistance than the unreinforced nickel. It is clearly illustrated by the values of the minimum creep rates and the time to fracture. For the composite is the minimum creep rate lower and time to fracture longer than for the pure nickel.

nickel, nanocomposite, creep

CIHLÁŘOVÁ, P.; ŠVEJCAR, J.

2007

1. 2. 2007

Acta Metallurgica Slovaka

Košice

1335-2393

Acta Mechanica Slovaca

13

2

Slovenská republika

16

20

4