Proceeding of International Conference on Green Technology ISSN:2355–3456 September 3rd, 2014, Semarang, Indonesia
Optimization of Temperature Nickel Chrome Coating to Get Best Quality of Hardness and Thickness of Steel ST 40 Edi Widodo1, Iswanto2 and Sudarmono Rizki Yulianto3 Muhammadiyah University of Sidoarjo, Sidoarjo, Indonesia
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Abstract—Corrosion is the destructive attack of an equipment made from metal. Chrome electroplating applied to prevent corrosion in the atmospheric oxidation of metals. This research subject to get the most optimize of temperature to the hardness number and corrosion resistance. ST 40 as Low carbon steel plated with a chromium as protective coating material. Variation of temperature applied to get the most optimum hardness number and corrosion resistance. Hardness number got with hardness test machine. Corrosion resistance got by corrosion test. Temperature raise give addition of thickness and hardness number. Its affect to the corrosion resistance. At the limit of 60 o C the thickness and hardness reduced its caused the ions adhered on surface of specimen got saturated. So its damage chrome coating at the surface of specimen. Keywords—optimizing, resistante
I.
hardness,
chrome
corrosion
INTRODUCTION
Metal corrosion was degradation of quality of metal material caused by electrochemistry reaction surface of material with its environment. This process will reduce usefulness of metal material. This process cannot be avoided. Most of industry equipment like machine element, built from metal, strength and easily to obtained. The corrosion not only caused by high concentration of vapor, temperature Operation also give contribution to the corrosion process. In this case material coating was needed to prevent high temperature and oxidation reaction to get corrosion resistance [1]. Chrome plating coat surface of metal with chromium. Chrome plating applied to some kind of metal like iron, steel, copper, ect. Its can applied also to plastics and nonmetallic materials. Chrome plating was electrolytic process utilizing a chromic acid and sulfuric acid based electrolyte.
Steel ST 40 had concentration of carbon 0,15 % , S = 0,05 %, P = 0,16 %. This mean it’s low carbon steel with tensile strength ≤ 40 kg/mm2. Applied for wide area of equipment, wire, nail, automotive equipments and the raw material of welded fabrication [2]. Chrome plating used to get hard metal coating, have high corrosive resistance and decorative. Electrolyte liquid to this process is chromic acid (H2CrO3), Pb as
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anode, stainless steel 304 with nickel coating as cathode. Anode and cathode inserted into the electrolyte solution and given electric current. Anode connected to the positive pole and cathode to the negative pole, causing the potential difference between the anode and cathode. In this process the lead metal does not decompose into the electrolyte solution and anode as conductor of electric current only. Through the electrolyte solution chromium ions will be carried away and stick to the surface of the cathode [3]. The reaction at the anode as follows : Oxygen output 2H2O → O2 + 4H+ + 4eChromate ions Oxidation 2Cr+ + 6H2O → 2CrO3 + 12 H+ + 6eProduction of lead dioxide Pb + H2O → 2PbO2 + 4H+ + 4eThe reaction at the PbO2 anode must be formed to avoid lead chromate which inhibits control concentration Cr+ in bath solution. The reaction at the cathode as follows: Hydrogen output 2H+ + 2e- → H2 Forming Cr Cr2O7-2 + 14H+ + 6e- → 2Cr3+ + 7H2O Nickel is used as a coating layer for chrome plating. Coating process in the electrolyte solution chloride sulfate, direct current electricity connected to a nickel as the anode and stainless steel 304 as the cathode. The anode will decompose into electrolyte solution containing nickel ions. The nickel ions carried away and stick to the cathode. Reduction reaction of nickel ions through electrons originating from a direct current source held in the cathode. Reduction reaction at cathode follows as: Ni2+ + 2e- → Ni 2H+ + 2e- → H2 The reaction occurs at the anode as follows: Ni → Ni 2+ + 2e4OH- + O2 → 2H2O + 4e2Cl- → Cl2 + 2e-
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Proceeding of International Conference on Green Technology ISSN:2355–3456 September 3rd, 2014, Semarang, Indonesia II.
METHODOLOGY
Specimens steel ST 40 cut 5 pieces size 15 x 4 cm thickness 5 mm. the specimens given treatment nickel chrome electroplating with nickel temperature variation of 40o C, 45o C,50o C, 55o C, 60o C. Specimens were coated then measured the hardness and corrosion resistance. A. Result of Research The effect of temperature on the process electroplating chrome coating reflects differences in the brightness of the coating results. The higher temperature given coating layer more bright and shiny. Temperature of 60 o C give the most glossy coating results compared with other temperatures. The higher temperature of coating will accelerate the velocity of reaction. As a result, more hydrogen atoms produced and lead to increased grain size. Thus the results of the brightness chromium layer will be more shiny. B. Thickness test Thickness of the specimen coated with chrome with variation of temperature measured with micrometer. Retrieval of data generated at random points are shown in Table 1. TABLE I.
Specimen Specimen 1 Temp 40º Specimen 2 Temp 45º Specimen 3 Temp 50º Specimen 4 Temp 55º Specimen 5 Temp 60º
I 5
Thickness (mm) II III IV 5 5 5
V 5
Rate (mm) 5
5,10
5,11
5,09
5,11
5,12
5,106
5,13
5,12
5,11
5,11
5,13
5,12
5,11
5,12
5,10
5,11
5,11
5,11
5,15
5,16
5,14
5,15
5,12
5,144
5,13
5,12
5,12
5,12
5,11
5,12
C. Hardness test Hardness number of steel ST 40 after coated with chromium measured with universal hardness tester. Data generated at random points on the specimen and the results are shown in Table 2. TABLE II. RESULT OF HARDNESS TEST Specimen
Test 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
Specimen Specimen 1 temp 40º Specimen 2 temp 45º Specimen 3 temp 50º Specimen 4 Temp 55º Specimen 5 temp 60º
2,5
2,5
2,5
2,5
2,5
2,5
Brinell test number (kg/mm2) 230 HB 30 250 HB 30 283 HB 30 339 HB 30 333 HB 30 339 HB 30 329 HB 30 339 HB 30 347 HB 30 339 HB 30 352 HB 30 339 HB 30 371 HB 30 339 HB 30 352 HB 30 323 HB 30 347 HB 30 366 HB 30
rate (kg/mm2) 254,3 HB 30 337 HB 30 338,3 HB 30 343,3 HB 30 354 HB 30 345,3 HB 30
400 300 200 100 0
Specimen
rate of thickness test
thicness (mm)
Indentation Diameter (mm)
rate of hardness number hardness (kg/mm2)
Specimen
TABLE THICKNESS TEST OF SPECIMEN
will increasing the thickness chromium layer. At temperature 60 o C decrease thickness of coating layer occurs, due to the saturation of the ion to stick to the specimen.
5,2 5,15 5,1 5,05 5 4,95 4,9
Figure 2. Rate of hardness test
III.
Spesimen
Figure 1. Rate of thickness test
Chrome plating with temperature variation cause an increase thickness of coating. The increasing temperatures in the coating process resulting impact on the increase energy and will accelerate the ions release. Its accelerate the movement of electrons from positive ions toward the negative ions. The chromium ions that settles on the surface of the material and leads to increase in size of the crystal. Deposition of ions on the surface of the material
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CONCLUSIONS
Material hardness testing aims to determine the resistance of a material to plastic deformation. Data of hardness testing show the difference number of specimen before and after coating. Hardness number 254 HB after coated Ni increase significantly to 337 HB. The nickel layer has the function to increase the hardness of the surface. Temperature variation in the electroplating process causes differences in surface hardness value of specimen. Hardness number tended to increase after coated surface. The result of hardness test showed that the optimum value reached with temperature of 55 0 C for 354 HB. Whereas at 60 o C hardness number get down. This indicates that the temperature of 55 0 C in the electroplating process provide the best current conductivity and the optimum of chromium ions mobility to the cathode to form a precipitate reached.
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Proceeding of International Conference on Green Technology ISSN:2355–3456 September 3rd, 2014, Semarang, Indonesia The higher temperature caused more of chromium ions attached to the surface of the specimen, and the more dense chrome coating caused the surface density of the specimen increase. The optimal coating reached at 55 o C. the chromium ions that attach to the surface of the specimen reached saturation properties after reach 55 o C of temperature. This condition will damage the specimen layer bond, resulting in decreased surface hardness of specimens. REFERENCES [1]
[2]
[3]
[4]
Basmal, “Pengaruh Suhu Larutan Elektrolit dan Waktu Pelapisan Tembaga pada Plat Baja Lunak terhadap Nilai Ketebalan”, Politeknosains Vol. XI No.1, 2012. Setiadji, Widya Mukti, “Perubahan ketangguhan Bahan ST.40 Yang Telah Mengalami Proses Double Hardening dengan Carburizing”, Universtitas Negeri Semarang. Semarang, 2007. Nani Mulyanigsih, Priyo Tri Iswanto, Sukrisno, “Pengaruh Waktu Elektroplating Nickel Khrom terhadap Kekerasan Baja Stainless Steel AISI 304”, Prosiding Seminar Nasional Aplikasi Sains & Teknologi (SNAST) Periode III, 2012. Protsenko, V.S., V.O. Gordiienko, F.I. Danilov, S.C. Kwon, “Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath.” E-Journal of Chemistry, 2011.
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