PENGARUH TEGANGAN, SUHU DAN WAKTU PELAPISAN HARD CHROME TERHADAP KEAUSAN DAN KEKERASAN LAPISAN PADA BAJA AISI 1045 TANPA DAN DENGAN PENGERASAN

I Gusti Ngurah Suarsana, Dr. Ir. Viktor Malau, DEA

2009 | Tesis | S2 Teknik Mesin

Tujuan penelitian untuk mengetahui pengaruh tegangan, suhu dan waktu pelapisan krom keras terhadap kekerasan permukaan lapisan dan keausan spesifik lapisan. Tegangan, suhu dan waktu diinteraksikan untuk mendapatkan kondisi optimum proses pelapisan (pelapisan paling efektif) yang mampu menghasilkan kekerasan lapisan permukaan paling maksimum dan keausan spesifik lapisan permukaan paling minimum. Spesimen baja AISI 1045 termasuk baja karbon menengah (= 0,411 %C) berbentuk silinder dengan diameter = 10 mm, panjang = 400 mm. Spesimen dibagi dua kelompok, kelompok pertama dikeraskan sebelum dilapisi, kelompok kedua tanpa dikeraskan langsung dilapisi. Variabel bebas: voltase (3, 4,5, 6, dan 9 volt), suhu (40, 45, 55, dan 60 ºC), dan waktu pelapisan (30, 40, 50, dan 60 menit). Uji kekerasan mengacu metoda Vickers beban = 0,250 kg (= 250 gr), dan uji keausan spesifik mengacu metoda Ogoshi dengan beban = 1 kg (= 1000 gr). Hasil uji kekerasan dan keausan spesifik menunjukkan, kekerasan permukaan spesimen dasar (raw material) = 190,00 VHN, kekerasan tertinggi permukaan lapisan krom keras spesimen dasar tanpa dikeraskan = 928,00 VHN (peningkatan = 388,42 % dibanding kekerasan raw material), pada spesimen dasar dikeraskan dilapisi krom keras = 1132,00 VHN (peningkatan = 495,79 %). Keausan spesifik permukaan spesimen dasar (raw material) = 3,4877E-04 mm²/kg, keausan spesifik terendah lapisan krom keras spesimen dasar tanpa dikeraskan = 1,1644E-08 kg/mm2 (turun = 99.67 % terhadap keausan spesifik raw material), sedangkan keausan terendah spesimen dikeraskan dan dilapisi krom keras = 8,7693E-09 kg/mm2 (turun = 99,75 %). Hasil tersebut merupakan hasil optimum pada kondisi pelapisan voltase 6 volt, suhu 55 ºC, dan waktu 50 menit, karena pada kondisi tersebut terjadi ikatan atom (adhesi) yang kuat antara logam dasar AISI 1045 dengan logam krom. Disamping itu secara visual hasil pelapisan pada kondisi tersebut lebih cerah. Hasil pengujian bila dikaitkan sifat mekanis bahan pada kondisi sama menunjukkan bahwa peningkatan kekerasan lapisan akan menghasilkan ketahanan aus spesifik lebih baik.

The objectives of this research want to know the influence of voltage, temperature and plating time for hard chrome towards hardness of surface plating and specific-wear of surface plating. From interaction of voltage, temperature and plating time taken an optimum condition plating process (most of effective plating) that can to produce most of maximum plating surface hardness and most of minimum plating surface specific-wear Specimens of this research are intermediate carbon steel AISI 1045 (= 0.411 % C), cylindrical forms with dimension: 10 mm diameter and 400 mm length. Specimens divided two groups, first group is hardened before plating and second group without hardened but directed plating. Independent variables: voltage (3, 4.5, 6, and 9) volt, temperature (40, 45, 55, and 60) ºC, and plating time (30, 40, 50, and 60 minute). Hardness test used Vickers method with load of 0.25 kg (= 250 gr) and surface specific-wear test used Ogoshi method with wear force of 1 kg (= 1000 gr). The results of hardness and specific wear test of surface hardness value of base specimen (raw material) = 190.00 VHN, The highest surface hardness base specimen with hard chrome plating = 928.00 VHN (increased = 388.42 % compared to raw material), For base specimen with hardened and hard chrome = 1132.00 VHN (increased = 495.79 %). Surface specific-wear raw material = 3.4877E-04 mm²/kg, The lowest surface specific-wear of specimen hard chrome plating without hardened = 1.1644E-08 kg/mm2 (descent = 99.67 % compared to raw material), while the lowest surface specific-wear specimen with hardened and hard chrome = 8.7693E-09 kg/mm2 (descent = 99.75 %). That the results be optimum values at plating condition: 6 volt of voltage, 55 ºC of temperature, and 50 minute of time, because in condition happen strong tie (adhesion) between metal base AISI 1045 with chrome metal. The other side of results for that condition looked bright and when the results correlated to mechanical character in self-same condition, the increasing surface hardness will be increasing specific surface wear-resistant. Keyword: electroplating, hard chrome, micro-hardness, surface specific-wear

Kata Kunci : elektroplating, krom keras, kekerasan mikro, keausan spesifik permukaan.