Korozijska postojanost nanostrukturiranih tvrdih metala

master's thesis

• Title (english): Corrosion resistance of nanostructured hardmetals
• Author: Ivan Majdak
• Mentor: Željko Alar (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2016-07-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Basic Technical Sciences; Materials

Abstract

Smanjivanjem veličine zrna tvrdog metala na nano razinu, dolazi do poboljšanja mehaničkih, ali i ostalih svojstava. Danas postoji nekoliko tehnologija kojima je moguće konsolidirati nanostrukturiran tvrdi metal. Najveći problem postizanja nano veličine zrna kod tvrdih metala je kontrola parametara koji utječu na rast istog tokom procesa sinteriranja. Isto tako, postavlja se pitanje kako nano veličina zrna utječe na korozijsku postojanost samog tvrdog metala. Da bi se to uvrdilo, potrebno je provest elektrokemijska ispititvanja u svrhu određivanja parametara korozije i analizirati ponašanje materijala u elektrolitu određene pH- vrijednosti.

U radu je analizirano osam uzoraka nanostrukturiranih WC-Co tvrdih metala, u cilju utvrđivanja njihove korozijske postojanosti. Uzorci su dobiveni konsolidacijom tri različita nano praha, različitih udjela WC i Co i različitim postupcima sinteriranja. Elektrokemijskim tehnikama određeni su korozijski parametri uzoraka; korozijski potencijal (Ecorr), gustoća korozijske struje (jcorr) i polarizacijski otpor (Rp). Ispitivanja su provedena u 3,5%-tnoj NaCl otopini pri sobnoj temperaturi.

Abstract (english)

Reducing the size of a carbide grain to a nano level, there is an improvement of mechanical and other properties. Today there are several technologies that can consolidate nanostructured hardmetal. The biggest problem of achieving nano-sized grains is parameters control which influence the growth of grain during the sintering process. Similarly, there is a question how nano grain size affects to the corrosion resistance of hardmetal. To identify that, it is necessary to perform electrochemical testings to determine the corrosion parameters and analyze the behavior of materials in the electrolyte of certain pH value.

In this paper, eight samples of nanostructured WC-Co hardmetal were analyzed in order to determine their corrosion stability. Samples were obtained by consolidation of three different nano powders, with different contents of WC and Co and different sintering processes. Corrosion parameters like corrosion potential (Ecorr), corrosion current density (jcorr) and polarization resistance (Rp) were determinated by electrochemical techniques. Measurements were perfomed in 3,5% NaCl solution at room temperature.

• Keywords: Tvrdi metali; nanostrukturirani WC-Co; korozija; elektrokemijska ispitivanja
• Keywords (english): Hardmetals; nanostructured WC-Co; corrosion; electrochemical testing
• Language: croatian
• URN:NBN: urn:nbn:hr:235:249156
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 16:53:13