Vpliv različnih matic na lastnosti kompozitnega tornega materiala : magistrsko delo

Čurila, Sven (author), Nagode, Aleš (mentor), Bizjak, Milan (comentor), Petric, Martin (comentor)

Zamenjava matice predstavlja najbolj intenziven poseg v kompozitni material, zato je potrebno pred zamenjavo materiala izvesti številna preizkušanja različnih materialnih lastnosti. V našem primeru se je pri izdelavi kompozitnih zavornih oblog iz proizvodnje umaknila matica tornega materiala iz fenol-formaldehidne smole. Namen magistrskega dela je bil poiskati ustrezen nadomestni material, ki bo imel primerne torne karakteristike, obrabne lastnosti in dobro temperaturno odpornost. Primerjali smo štiri vzorčne matice iz novolačne fenol-formaldehidne smole, ki se med seboj razlikujejo glede na tekočnost in dodatkov. Kompozitom z nadomestnimi maticami smo merili torne lastnosti na stroju Krauss in jih primerjali s kompozitom z referenčno matico. Obrabne mehanizme smo opredelili s pomočjo SEM analiz ter primerjali temperaturno odpornost z DSC analizo. Rezultati tornih preizkusov so pokazali boljše torne lastnosti kompozita iz srednje tekoče fenol-formaldehidne smole (µ = 0,49) v primerjavi z referenčnim tornim materialom s srednjo tekočo smolo in dodatkom fosforja (µ = 0,46). Rezultati DSC so pokazali, da je temperaturno najobstojnejši torni material iz srednje tekoče fenol-formaldehidne smole (do 470 °C), med tem ko je referenčni torni material iz srednje tekoče fenol-formaldehidne smole z dodatkom fosforja obstojen do 450 °C. Rezultati strižne trdnosti se med seboj bistveno ne razlikujejo, najvišjo strižno trdnost smo izmerili na tornem materialu iz srednje tekoče fenol-formldehidne smole (? = 11,38 MPa), najnižjo pa na referenčnem tornem materialu (? = 10 MPa). Rezultati obrabe so pokazali najmanjšo prostorninsko izgubo tornega materiala iz srednje tekoče fenol-formaldehidne smole (168 mm3) v primerjavi z referenčnim tornim materialom (193 mm3). Posnetki SEM kažejo najintenzivnejšo obrabo kompozita iz kratko tekoče fenol-formaldehidne smole z dodatki elastomerov NBR v primerjavi z ostalimi tornimi materiali iz fenol-formaldehidne smole. Mehanizem obrabe je pretežno abrazijski v obliki raz ter v obliki razslojevanja in področji z izpuljeno matico zaradi oksidacije in utrujanja. Za najbolj primeren material za matico se je izkazala novolačna fenol-formaldehidna smola srednje tekočnosti, ki ima dober potencial za uporabo v kompozitnem tornem materialu.

• Language: Slovenian
• Keywords: torni kompozitni material, fenol-formaldehidne smole, matica, obraba, trenje, mikrostruktura
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: S. Čurila
• Year: 2023
• Number of pages: XVI, 49 f.
• PID: 20.500.12556/RUL-152036
• UDC: 669
• COBISS.SI-ID: 173364227
• Publication date in RUL: 28.10.2023

Secondary language

• Language: English
• Title: Influence of different matrices on composite friction material properties : master's thesis

Abstract

Matrix replacement is the most important change in a composite and requires extensive testing of the material properties of alternative matrices prior to replacement. In our case, the matrix currently used in the manufacture of composite brake pads is no longer in use. The objective of this master's thesis is to find a suitable alternative matrix and evaluate the effects of replacement in terms of frictional properties, wear and temperature resistance. Four sample matrices of novolak phenol-formaldehyde resin were compared, which differ from flowability and additives. The samples of the composite friction material were tested for their frictional properties on a Krauss machine according to the reference composite friction material. Wear mechanisms were identified using light microscopy and analysis SEM and temperature resistance was compared using DSC analysis. The results of the friction tests showed better frictional properties of the composites with the medium-flow phenol-formaldehyde resin (µ = 0.49) compared to the reference composite (µ = 0.46). The DSC analysis results showed the highest temperature resistance of the medium-flow phenol-formaldehyde resin (T = 470 °C) compared to the reference resin (T = 450 °C). The shear strength results did not differ significantly. The lowest volume loss was measured on the medium-flow resin (168 mm3) compared to the reference material (193 mm3). SEM figures show the highest wear for the composite with short-flow resin with NBR elastomer additives. The wear mechanism is predominantly abrasive in the form of grooves, pitting, and in the form of delamination and areas of matrix tear-outs due to oxidation and fatigue. The most suitable alternative phenol-formaldehyde resin was a novolak-phenol-formaldehyde resin with medium flowability, which would be interesting for the production of a composite friction material.

• Keywords: friction composite material, phenol-formaldehyde resins, matrix, wear, friction, microstructure