Nanostrukturirani tvrdi metali s FeNi vezivom i dodatkom kubičnih karbida

master's thesis

• Title (english): Nanostructured hard metals with FeNi binder and cubic crystals addition
• Author: Zvonimir Petrović
• Mentor: Ljerka Slokar Benić (mentor)
• Mentor: Tamara Aleksandrov Fabijanić (pomoć pri izradi, neposredni voditelj)
• Committee member: Stjepan Kožuh (predsjednik povjerenstva)
• Committee member: Ljerka Slokar Benić (član povjerenstva)
• Committee member: Ivan Jandrlić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2022-01-19, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

su najvažniji predstavnici metalurgije praha. To su kompozitni materijali u kojima su čestice tvrde karbidne faze međusobno povezane metalnim vezivom, a koji najveću primjenu nalaze u industriji alata. Kako bi im se poboljšala svojstva, u zadnje vrijeme se proizvode iz ultrafinih nano čestica praha. Struktura dobivena sinteriranjem praha nanočestica osigurava značajno poboljšanje svojstava proizvoda, kao što su: veće brzine rezanja, manje tolerancije alata i duži vijek trajanja.
Cilj ovog rada bio je primjenom nano praha volframovog karbida postići homogenu sitnozrnatu mikrostrukturu koja će rezultirati visokim i ujednačenim vrijednostima tvrdoće po ispitnoj površini. Stoga je proizveden nanostrukturirani tvrdi metal WC-FeNi s dodatkom kubičnih karbida tehnologijom metalurgije praha točnije HIP postupkom, čija je sinterirana gustoća jednaka teorijskoj gustoći. Na poliranoj površini svjetlosnim mikroskopom nisu uočeni defekti, dok je pretražnom elektronskom mikroskopijom s emisijom polja uočen vrlo mali broj manjih pora. Tvrdoća proizvedenog nano tvrdog metala je izrazito visoka te ujednačena po ispitnoj površini, što je rezultat homogene mikrostrukture kao i dodatka inhibitora rasta zrna u obliku kubičnih karbida.

Abstract (english)

Hard metals are the most important representatives of powder metallurgy. They are composite materials in which particles of carbide phase are bonded by metal binder. A major application of this materials are in the tool industry. Recently, to improve the properties, they are produced from ultrafine nano powders. Structure obtained by sintering of nano powders provides much improvement of product properties, such as: higher cutting rates, lower tolerances of tools as well as longer service life.
The goal of this work was to obtain the homogenous finegrain microstructure that will result in high and uniform hardness values using the nano powders of tungsten carbide. For this purpose, nanostructured hard metals WC-FeNi with cubic crystals addition was produced by powder metallurgy, i.e. by HIP. Sintered density of produced material is identical to the theoretical density. No defects were detected on the polished surface by light microscopy, while a very small number of smaller pores were detected by scanning electron microscopy with field emission. The hardness of the produced nano-hard metal is extremely high and uniform over the test surface, which is the result of homogeneous microstructure as well as the addition of grain growth inhibitors in the form of cubic carbides.

• Keywords: metalurgija praha; nano-prahovi; nanostrukturirani tvrdi metali; tvrdoća
• Keywords (english): powder metallurgy; nano-powders; nanostructured hard metals; hardness
• Language: croatian
• URN:NBN: urn:nbn:hr:115:187727
• Study programme: Title: Graduate study program Metallurgy; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka metalurgije (magistar/magistra inženjer/inženjerka metalurgije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-02-17 09:00:41