EFFECT OF TRIBUTYLMETHYLAMMONIUM METHYL SULFATE (MTBS) ADDITION ON ELECTRODEPOSITION OF Ni-W ALLOY

• Main Author: Claudia Christanti, Cindy
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/42520
• Institution: Institut Teknologi Bandung

Hard materials such as Ni-W alloys are widely used in coating technology to protect other materials, i.e. in the aerospace and automotive industries. Various methods have been carried out to synthesize Ni-W alloys including powder metallurgy, ball milling, sputtering and electrodeposition. Among these methods, one of the easiest and most economical methods is the electrodeposition method. The principle of the electrodeposition method is to synthesize metal alloys from the salts dissolved in an electrolyte solution. Ni-W alloy was commonly synthesized from nickel (11) chloride and sodium tungsten as the nickel and tungsten precursor, respectively. In its development, the additives were added to increase the concentration of W. Increasing the concentration of W in Ni-W alloy will increase the hardness and corrosion resistance of the alloy. In addition, homogeneity and particle density also influence the hardness of Ni-W alloys. However, optimum conditions of electrodeposition that can increase the hardness ofNi-W alloy have not been reported. In this research, the effect of ammonium ion, tributylmethylammonium methyl sulfate ( MTBS) was added, on the electrodeposition process of Ni-W alloys. Variation of conditions for the synthesis of Ni-W alloys before the addition ofMTBS, such as electrodeposition temperature with a range of 50-90°C, pH of the solution with a range of 4-1 0 and electrodeposition current with a variation of 10- 150 mA was carri c,;t 2t t2 2 min 2 timm m2Hi r., We used 2 electrodes in this deposition , brass substrate as a cathode and carbon as an anode. We obtained that the optimum conditions for synthesizing Ni-W alloy were at temperature 75 oc, pH 8.9 and 100 mA current. In addition, heat treatment of the deposit results was also observed. Ni-W alloys are heated at 600 oc for 6 hours in an argon gas atmosphere. The crystalline phase of the deposited sample was identified based on the typical diffraction peak ofNi-W alloy at 28 at 44°, 51°, and 75° Based Ill on the Scherrer equation, obtained that the crystallite size of Ni -W alloy and Ni ­ W/MTBS alloy are 4. 15 nm and 3.5 nm , respectively. SEM images revealed that Ni­ W and Ni-W MTBS alloys have a granular shape. Using EDX, we obtained that the atomic percent of W in Ni-W and Ni-WIMTBS alloy are 8.14% and 6.07 %, respectively. Before heat treatment, the hardness values ofNi-W and Ni-WIMTBS are 8.5 ± I and 9. 08 ± I GPa, respectively. When the Ni-W deposit was heated to a temperature of around 600 oc for 6 hours in an argon gas atmosphere, the hardness increases by 31.7% (11.2 ± 0. 8 GPa) forNi-W alloys and 60% (13,6 ± 1 GPa) forNi­ W/MTBS. In addition, the crystal size increased to 26,5 nm in the Ni -W alloy and 22,68 nm in the Ni-W/MTBS alloy. Corrosion resistance testing ofNi-W and Ni-W I MTBS alloys was carried out in 3% NaCl solution. The Nyquist curve generated from the EIS measurements showed that the Ret value of Ni- W alloys was greater than 3595 n. cm2 compared toNi -W I MTBS Ni-W alloy deposits were 531.7 n cm2 using 0. 2 M MTBS. While the corrosion rate ofNi-W alloy deposits was obtained from Tafel polarization measurements which were 0.03 mmpy and 0.07 mmpy with the acquisition of 0.2 M MTBS. The effect of heat treatment on the corrosion resistance ofNi -W alloy deposits increase. The Ret value of the Ni-W alloy deposit after heat treatment increased to 41870 n cm 2 and 919400 n cm2 with the addition of0. 2 M MTBS. While the corrosion rate becomes slower, 0.0534 mm I year and 0.0302 mm I year for Ni -W alloys with an addition of 0.2 M MTBS.