Braking Performances of Brake Pad for Passenger Car

Enam pad brek yang telah dibangunkan melalui teknik serbuk metalurgi telah menjalani ujian prestasi di atas jalan mengikut “Annex 3 Economic European Community Regulation 13 (ECE R13)”. Setiap sampel telah menjalani ujian sejuk, pudar dan pemulihan. Keputusan ujian menunjukkan hanya sampel S2, S14, S27 dan S31 menepati keperluan minimum purata nyah pecutan terhasil (PNPT). Kajian ke atas perubahan mikrostruktur permukaan haus pad brek telah diperhatikan menggunakan teknik kemikroskopan elektron imbasan (KEI) beserta analisis tenaga terserak Spektroskopi (TTS). Pemeriksaan mikrostruktural ke atas permukaan haus mendapati lapisan geseran adalah tidak berterusan dan tidak menutupi keseluruhan permukaan. Apabila kajian mendalam dijalankan ke atas lapisan geseran, diperhatikan mekanisme haus lelasan, rekatan dan nyah lapisan berlaku semasa proses pembrekan. Lazimnya, suhu permukaan meningkat disebabkan peningkatan tenaga kinetik yang diserap oleh pad/piring brek semasa pembrekan. Pekali geseran menurun dengan peningkatan suhu permukaan disebabkan penguraian bahan organik di dalam komposisi pad brek. Mekanisme haus dan kegagalan haba menyebabkan kegagalan plastik pada permukaan setempat, menghasilkan partikel haus dalam berbagai saiz, bentuk dan kimia. Kata kunci: Pad brek; pekali geseran; MFFD; pudar haba; prestasi di atas jalan Six prototype brake pads developed through powder metallurgy technique were subjected to on–road performance tests in accordance with Annex 3 Economic European Community Regulation 13 (ECE R13). Each sample was subjected to cold, fade, and recovery tests. Test results show that only sample S2, S14, S27 and S31 comply with the minimum requirements of mean fully developed deceleration (MFDD). Microstructural changes are studied on the worn surface of the brake pad using Field Emission Scanning Electron Microscope (FESEM) and Energy Dispesive spectroscopy (EDS). Microstructural examination on the worn surface revealed that friction layer was discontinuous and did not cover the whole surface. When detailed study is performed on the friction layer, it was observed that several mechanisms of wear such as adhesion, abrasion, and delamination took place during braking process. Generally, surface temperature increases due to the increase in kinetic energy absorbed by the brake pad during braking. The friction coefficient decreases with increasing surface temperature due to degradation of organic materials in the brake pad composition. These wear mechanisms and thermal failures result in plastic collapse in the local region, producing wear particles in different sizes, shapes and chemistry. Key words: Brake pad; friction; MFFD; heat fade; on–road performance