Tvrdoća i lomna žilavost nanostrukturiranog tvrdog metala

undergraduate thesis

• Title (english): Hardness and fracture toughness of nanostructured cemented carbides
• Author: Božo Renić
• Mentor: Danko Ćorić (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-03-01, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

U ovom radu opisani su tvrdi metali uz naglasak na njihova mehanička svojstva, mikrostrukturu, primjenu i način proizvodnje. U eksperimentalnom dijelu ispitivane su i analizirane vrijednosti tvrdoće i lomne žilavosti nanostrukturiranih tvrdih metala. Eksperimentalni dio uključivao je provođenje ispitivanja na tri uzorka: s 5% kobalta (WC-5Co), 10% kobalta (WC-10Co) odnosno 15% kobalta (WC-15Co). Tvrdoća je ispitana metodom po Vickersu (HV30) sukladno normi HR EN ISO 6507-1:2005, a lomna žilavost određena je Palmqvistovom metodom sukladno normi ISO 28079:2009. Kod Palmqvistove metode mjerene su duljine pukotina koje propagiraju iz vrhova otiska. Rezultati pokazuju da se s povećanjem udjela kobalta u tvrdom metalu smanjuje tvrdoća, a lomna žilavost povećava. Također ukazuju da se primjenom nanostrukturiranih tvrdih metala, nano veličine zrna, povećava tvrdoća uz neznatnu promjenu lomne žilavosti.

Abstract (english)

In this paper hard metals are described with an emphasis on their mechanical properties, microstructure, application and production method. In the experimental part, the hardness and fracture toughness of nanostructured hard metals were tested and analyzed. The experimental part included tests on three samples: with 5% cobalt (WC-5Co), 10% cobalt (WC-10Co) and 15% cobalt (WC-15Co). The hardness was tested by Vickers method (HV30) according to HR EN ISO 6507-1:2005. and the fracture toughness was determined by the Palmqvist method according to ISO 28079: 2009. Palmqvist's method measures the length of cracks that propagate from the corners of the impression. The results show that with the increase of the cobalt share in the hard metal hardness decreases and the fracture toughness increases. They also indicate that using nano-structured hard metal, nano-sized grains, increases the hardness with a slight change of fracture toughness.

• Keywords: nanostrukturirani tvrdi metali; tvrdoća; lomna žilavost
• Language: croatian
• URN:NBN: urn:nbn:hr:235:342622
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 0000-00-00
• Created on: 2019-05-22 21:37:54