TW574414B - Process for producing Al2O3 ceramic coating on MAR-M247 superalloy by electrolytic deposition - Google Patents

Abstract

A process for producing an Al2O3 ceramic coating, such ceramic are formed by electrolytic deposition an aluminum hydroxide film in an aqueous solution of aluminum nitrate (Al(NO3)3) on MAR-M247 superalloy substrate. The electrolytic deposition aluminum hydroxide film is then sintered under conditions sufficient to a result in a protective Al2O3 ceramic coating for high temperature oxidation and corrosion.

Description

574414, 五、發明說明（l) 、 因近年來，對飛機性能要求提高，而使超合金的操作 運，溫度要更高，所處的璆境愈來愈嚴苛；因此對超合金 的南溫強度和耐高溫腐蝕性的要求更加重視。 超合金的高溫強度來自於添加A1、Ti的析出強化，添 加Mo、W、Ta做為固溶強化，以增強高溫的機械性質，添 加Cr、Ay、Si ’形成安定的氧化物形成很好的保護性氧化 膜；但若A1、Ti加入太多，而造成晶界處含鋁量過高的偏 =現像時會嚴重影響到其高溫抗潛變（Creep)能力；Cr含 ，太多會析出其他相使高溫強度劣化，M〇、w、Ta添加過 多除減少Cr的固溶量也損及其高溫抗蝕性；所以要提高抗 餘性又要面強度便要有所取捨。 ,本發明為克服此困難，而此用表面改質的方法，為一 種形成Α ΙΑ陶瓷鍵層方法，此陶究被覆層是以電解沉積的 方法在硝酸銘水溶液中沉積氫氧化鋁水合物於MAR_M247超 合金基材表面再經燒結以得到抗高溫氧化及腐蝕丨2 %陶 瓷被覆層。 近年來為提高超合金的高溫性質而有多項的表面改質 技術的出現，有滲鋁、鋁化處理、電漿 、物理氣相沉積（PVD)(包含濺鍍法（sputtering))、化學 氣相沉積（CVD)與溶膠-凝膠（s〇1_gel c〇ating)等方法出 現。574414, V. Description of the invention (l) Due to the increased requirements for aircraft performance in recent years, the operation and operation of superalloys must be higher, and the environment in which they are located is becoming more and more severe; More attention is paid to the requirements of temperature strength and high temperature corrosion resistance. The high-temperature strength of superalloys comes from the precipitation strengthening of the addition of A1, Ti, and the addition of Mo, W, and Ta as solid solution strengthening to enhance the high-temperature mechanical properties. The addition of Cr, Ay, and Si 'forms a stable oxide. Protective oxide film; however, if A1 and Ti are added too much, the aluminum content at the grain boundary will be too high = the current image will seriously affect its ability to resist high temperature creep (Creep); if Cr is contained, too much will precipitate Other phases degrade the high-temperature strength. Too much addition of Mo, W, and Ta reduces the solid solution amount of Cr, which also damages its high-temperature corrosion resistance; therefore, to improve the residual resistance, the surface strength must be selected. In order to overcome this difficulty, the present invention uses a surface modification method to form a ΑΙΑ ceramic bond layer. This ceramic coating is an electrolytic deposition method for depositing aluminum hydroxide hydrate in an aqueous solution of nitric acid. MAR_M247 superalloy substrate surface is then sintered to obtain high temperature oxidation and corrosion resistance 2% ceramic coating. In recent years, a number of surface modification technologies have appeared to improve the high temperature properties of superalloys, including aluminizing, aluminizing, plasma, physical vapor deposition (PVD) (including sputtering), and chemical gas. Phase deposition (CVD) and sol-gel (so-gel co-ating) methods have appeared.

本發明是以電解沉積方式於硝酸鋁水溶液中製備A 陶曼被覆層於MAR-M247超合金上，主要的反應步驟如下： 1 ·硝酸鋁的解離The present invention uses electrolytic deposition to prepare A Taoman coating on MAR-M247 superalloy in aluminum nitrate aqueous solution. The main reaction steps are as follows: 1. Dissociation of aluminum nitrate

574414、 玉、發明說明（2) A1(N03)3 — Al3+ + 3N03- 2· 2A13+(H20)3 · H20水合離子生成 2A13+ + 7H20 — 2A13+(H20)3 · H20 3·氫氧化鋁水合物（2A1(0H)3+ · H20)的形成 2A13+(H20)3 · H20 + 6e_ —2Al(〇H)3 · H20 + 3H2 4 ·氫氧化鋁水合物乾燥與燒結成氧化鋁 2A1(0H)3 · H20 Al2〇3 + 4H2〇 ^本發明的製程是以低濃度的錄液及適當的電壓沉積氳 氧化鋁水合物薄膜，再經燒結得到^…薄膜。經此處理後 的MAR-M247超合金確能提高材料抗氧化及抗腐蝕能力。其 塗層均勻性問題取決於電場的分布，只要電場分布均勻， 所得之膜厚亦為均勻。本方法具有下列優點： 1 ·所需之設備便宜且易取得。 2·形狀複雜之工件不受限制，亦可得均勻鍍膜。 3.低溫製程所得之粉末或鍍膜其純度較高。 4^和㈣能以電化學參數控制，辅以燒結參數得 理想之陶瓷鍍膜。574414, Jade, Description of the invention (2) A1 (N03) 3 — Al3 + + 3N03- 2 · 2A13 + (H20) 3 · H20 hydrated ions to form 2A13 + + 7H20 — 2A13 + (H20) 3 · H20 3 · aluminum hydroxide hydrate ( 2A1 (0H) 3+ · H20) Formation 2A13 + (H20) 3 · H20 + 6e_ — 2Al (〇H) 3 · H20 + 3H2 4 · Aluminum hydroxide hydrate is dried and sintered to alumina 2A1 (0H) 3 · H20 Al2O3 + 4H2O ^ The process of the present invention is to deposit a thin film of alumina alumina hydrate with a low-concentration recording solution and an appropriate voltage, and then sinter to obtain a thin film. After this treatment, the MAR-M247 superalloy can indeed improve the material's resistance to oxidation and corrosion. The coating uniformity problem depends on the electric field distribution. As long as the electric field distribution is uniform, the resulting film thickness is also uniform. This method has the following advantages: 1. The required equipment is cheap and easily available. 2. Complex shapes of workpieces are not restricted, and uniform coating can also be obtained. 3. The purity of the powder or coating obtained by the low temperature process is high. 4 ^ and ㈣ can be controlled by electrochemical parameters, supplemented by sintering parameters to obtain ideal ceramic coatings.

574414,574414,

發明由實驗發現適當的乾燥 微小，甚至沒有裂缝的覆膜 到最佳的保護效果，而能大 運用於飛機喷射引擎更為出 處理外相關細節敘述如下： (1)陰極極化 方法此得到分佈均勻且裂缝極 ，及適當的燒結條件使基材得 幅度提升多方面的性質，使其 色。本製程如圖一所示，除前 MAR-M247超合金試片在〇.1M、〇〇1M、〇〇〇im之硝酸 鋁水溶液（pH值分別為2. 7、3.4及3·9)，採用飽和氣化銀 電極（AgCl)為參考電極，碳棒為輔助電極。以恆定電位儀According to the invention, it is found through experiments that the appropriate dry, even crack-free coating is the best protection effect, and can be widely used in aircraft jet engines. The details are described as follows: (1) Cathodic polarization method is obtained. Uniform and extremely cracked, and proper sintering conditions make the substrate have a wide range of properties and make it color. This process is shown in Figure 1. Except for the former MAR-M247 superalloy test piece in aluminum nitrate aqueous solution (pH values of 2.7, 3.4, and 3.9) at 0.1M, 0.001M, and 0.0000, A saturated vaporized silver electrode (AgCl) is used as a reference electrode, and a carbon rod is used as an auxiliary electrode. Potentiostat

(EG&G Model 273A Potentiostat)在 〇.5mV/sec 之掃描速 率由0V至4V測其陰極極化曲線。發現整個過程可能發生的 反應有· H+ + e- H2 2A13+(H20)3 · H20 + 6e· — 2A1(0H)3 · H20 + 3H2 2 A13+ (H2 0 )3 · H2 0離子的擴散極限 2H20 + 2e_ — H2 + 20H- (2)定電位電解沉積(EG & G Model 273A Potentiostat) measured its cathode polarization curve from 0V to 4V at a scan rate of 0.5 mV / sec. It is found that the reactions that can occur throughout the process are: H + + e- H2 2A13 + (H20) 3 · H20 + 6e · — 2A1 (0H) 3 · H20 + 3H2 2 A13 + (H2 0) 3 · H2 0 ion diffusion limit 2H20 + 2e_ — H2 + 20H- (2) Constant potential electrolytic deposition

電解沉積氧化鋁過程的參數有很多，本實驗主要在沉 積電位、沉積時間和鍍液濃度三個參數對沉積薄膜的影 響。由實際的定電位電解沉積氧化鋁在三種濃度中鍍液中 所得最佳電位如表一所示。沉積時間過長會使鍍膜不均勻 及厚度大而在乾燥或燒結過程中會有較大的應力造程膜的 破裂；本實驗發現由適當沉積時間可得到一良好的薄膜， 此三種濃度的最佳條件如表一所示。由陰極極化取線可知There are many parameters for electrolytic deposition of alumina. This experiment mainly focuses on the effects of three parameters, ie, deposition potential, deposition time, and bath concentration, on the deposited film. Table 1 shows the optimal potentials obtained from the actual constant potential electrolytic deposition of alumina in the plating solution in three concentrations. If the deposition time is too long, the coating will be uneven and thick, and the film will be cracked during the drying or sintering process. This experiment found that a good film can be obtained by appropriate deposition time. The best conditions are shown in Table 1. It can be known from the cathodic polarization

第7頁 574414、 五、發明說明（4) ^ ^ ^ 當濃度增加時pH值越低，也就是氫離子濃度題高，而使反 應速率加快也就是電流密度變大，造成電解沉積過快使得 j膜均勻性變差而使得覆膜會有裂縫產生。使實驗得到適 當的硝酸鋁濃度及其相對電位和沉積時間如表一所示。本 =明特點是依據實驗發現以較低的硝酸鋁濃度、低的電流 ^度及較短的沉積時間所得的薄膜再經適當的乾燥及燒結 可獲得良好的氧化鋁薄膜。從薄膜厚度的量測，得知鍍膜 厚度低於1 μιη可得到無裂縫的鍍膜，厚度大於12//m以上 則有明顯的裂痕，厚度的控制對氧化鋁薄膜的質 響很大。本發明所得知的遒當薄膜厚度如表—所^質 (3 )乾燥與燒結 ^試片上所沉積的薄膜在乾燥過程容易因膠體内所含水 伤，發時產生龜裂現象，本實驗發現以^75%相對濕度下 乾燥可以避免因水份蒸發速率過快造成大量的裂縫形成。 經乾燥過後的沉積薄膜仍是含有吸附水份的氫氧化鋁水合 ，，需要完全去除水份與氫氧化鋁的縮合反應後才會形成 氧化鋁。由熱重差分析（TGA/DTA)，發現氩氧化鋁水合物 在燒結加熱過程中有兩個溫度有重量劇減的現象，其重量 劇減是因水分子脫離所造成的，因此本發明是控制此兩溫 度(知8 0〜120 C及20 0〜350。〇維持一定的時間（5〜15分鐘）， 待氫氧化鋁水合物在此兩溫度等溫下大量的去除水份後再 升溫至400〜480 °C維持5〜15分鐘進行縮合反應，最後升溫 至45〇〜i〇〇(TC維持2〇〜18〇分鐘，如圖二所示，如此可避免 或減少在燒結過程中所造成的裂縫。由XRD分析發現此製Page 7 574414, V. Explanation of the invention (4) ^ ^ ^ When the concentration is increased, the lower the pH value, that is, the higher the concentration of hydrogen ions, and the faster the reaction rate, that is, the larger the current density, the faster the electrolytic deposition makes j film uniformity becomes worse, so that cracks may occur in the film. Table 1 shows the appropriate aluminum nitrate concentration, relative potential, and deposition time. The characteristics of the present invention are based on the experimental findings that a thin film obtained with a lower aluminum nitrate concentration, a lower current, and a shorter deposition time can be properly dried and sintered to obtain a good alumina film. From the measurement of the film thickness, it is known that a coating film with a thickness of less than 1 μm can be obtained without cracks, and a thickness of more than 12 // m has obvious cracks. The thickness control has a great effect on the quality of the alumina film. The thickness of the known thin film obtained in the present invention is as shown in Table-(3) Drying and sintering. The thin film deposited on the test piece is easily damaged by water in the colloid during the drying process, and cracks occur when it is generated. This experiment found that Drying at ^ 75% relative humidity can avoid the formation of a large number of cracks due to the rapid evaporation of water. After drying, the deposited film still contains hydrated aluminum hydroxide, which needs to be completely removed before the condensation reaction between water and aluminum hydroxide is formed. From the TGA / DTA analysis, it was found that during the sintering and heating process of argon alumina hydrate, there are two phenomena where the weight decreases sharply. The weight reduction is caused by the detachment of water molecules, so the present invention is Control these two temperatures (known as 80 ~ 120 C and 20 ~ 350.) Maintain a certain time (5 ~ 15 minutes), wait for the aluminum hydroxide hydrate to remove a large amount of water at these two temperatures and then increase the temperature. It is maintained at 400 ~ 480 ° C for 5 ~ 15 minutes to conduct the condensation reaction, and finally heated to 45 ~~ 100 (TC is maintained for 20 ~ 180 minutes, as shown in Figure 2). This can avoid or reduce the impact of sintering process. The crack caused by XRD analysis found this system

第8頁 57441( 五、發明說明（5) 秋可以在較低的溫度下獲得0相的氧化|g。在極化腐钱試 驗發現緻密之氧化鋁鍍膜可避免孔蝕的侵害。根據刮痕試 驗顯示此法所製備之氧化鋁薄膜於MAR-M247超合金上之結 合力大於基材的降伏強度。經9 0 0。(：熱重分析（TGA)發現被 覆氧化鋁的抗氧化能力有明顯的提升。本發明之製程如圖 一所示，其分為四步驟：〇)前處理（2)電解沉積（3)乾燥 (4)燒結。較具體說明如下敘述： (1)前處理 將剪裁成直徑少15 mm，厚度0· 2 mm之圓形試片後以 水砂紙研磨，依序為# 24〇、# 4〇〇、# 6〇〇、# 8〇〇、# ^00、#1500，接著再以之氧化鋁粉末拋光至亮 面^經過清潔劑洗淨後，置入Na〇H中以超音波震盪器震盪 1〇分鐘，再置入丙酮中以超音波振盪機振盪1〇分鐘，以 到去潰的效果。最後以去離子水洗淨，並自然陰乾。 (2)電解沉積 以Α1(Ν〇3)3水溶液為電 於臨界電位尋找最佳電 以碳棒為陽極，試片為陰極 解液。配合陰極極化曲線的範圍 解電位進行電解沉積。 (3)乾燥 ，而作緩慢 75%的相重士 ，避免乾燥過程蒸發速度過快而產生裂縫 、、乾燥程序，置於恆溫恆濕爐中控制於30 °C， 濕度下進行乾燥。 (4 )燒結 乾燥後的試片仍含有吸附少量水份的氫氧化铭水合Page 857441 (V. Description of the invention (5) Autumn can obtain 0-phase oxidation | g at a lower temperature. It was found in the polarization corrosion test that the dense alumina coating can avoid pitting damage. According to scratches The test shows that the bonding force of the alumina film prepared by this method on the MAR-M247 superalloy is greater than the drop strength of the substrate. After 900. (: Thermogravimetric analysis (TGA) found that the coated alumina has significant oxidation resistance The process of the present invention is shown in Figure 1. It is divided into four steps: 0) pretreatment (2) electrolytic deposition (3) drying (4) sintering. The more specific description is as follows: (1) the pretreatment will be tailored After forming a circular test piece with a diameter of 15 mm and a thickness of 0.2 mm, it was ground with water sandpaper in order, # 24〇, # 4〇〇, # 6〇〇, # 8〇〇, # ^ 00, # 1500 , And then polished with alumina powder to a bright surface ^ After washing with detergent, put it in NaOH to oscillate with an ultrasonic oscillator for 10 minutes, and then put it into acetone and oscillate with an ultrasonic oscillator for 10 minutes In order to achieve the effect of decompression. Finally, wash with deionized water and dry in the shade. (2) Electrolytic deposition with A1 (Ν〇3) 3 water-soluble To find the best electricity at the critical potential, use a carbon rod as the anode and the test piece as the cathode solution. Electrolytic deposition is performed with the solution potential of the cathodic polarization curve. (3) Dry and make the phase 75% slower To avoid cracks and drying procedures caused by too fast evaporation during the drying process, put it in a constant temperature and humidity furnace and control it at 30 ° C, and dry it under humidity. (4) The sintered and dried test piece still contains a small amount of water. Hydroxide hydroxide

第9頁 574414、Page 9 574414,

^ 經多步驟燒結過程方能將水份去除及縮合反應才會 侏成^化紹，燒結過程如圖二所示。經由不同的實驗條 得到二種濃度相對應之最佳電位及沉積時間如表一： 表一 電位mV 時間 厚度// m 1100 500 0.8-1.2 10 00 30 0 0.8-1.2 950 200 0 · 8 -1 · 2^ Only after the multi-step sintering process can moisture removal and condensation reaction take place. The sintering process is shown in Figure 2. The optimal potentials and deposition times corresponding to the two concentrations obtained through different experimental strips are shown in Table 1: Table 1 Potential mV Time Thickness // m 1100 500 0.8-1.2 10 00 30 0 0.8-1.2 950 200 0 · 8 -1 · 2

濃度C 酸鹼pH 0.001 3. 9 0 · 〇 1 Λ 燒結條件參數如表二所示： 表二 溫度 T3，°c 450 500 600 700 800 900 時間 t3，min 1 20 1 20 90 90 9〇 9〇 由電化學極化試驗及TGA試驗發現經電解沉積氧化銘之試 片於7J)(rc，燒結90分鐘之抗蝕性及抗氧化性有明顧的提 ，。試片於3· 5%NaCl水溶液中之試驗結果如表三，經被覆 氧化鋁試片之腐蝕電流密度顯著下降，孔蝕電位（相較於 甘汞參考電極）顯著提升。、試片於9 〇(rc大氣中進瞎 •ίΐίΐ試驗，如圖三，顯示被覆氧化銘試片其抗氧化能 表三 孔蝕電位（V) 〇. 855 〇. 225 試片種類 腐蝕電流密度（/zA/cm2) MAR-M247 基材 13.5 被覆氧化鋁試片 1.7Concentration C pH 0.001 3. 9 0 · 〇1 Λ The parameters of the sintering conditions are shown in Table 2: Table 2 Temperature T3, ° c 450 500 600 700 800 900 Time t3, min 1 20 1 20 90 90 9〇9〇 Electrochemical polarization test and TGA test found that the electrolytically deposited test piece was tested at 7J) (rc, and the corrosion resistance and oxidation resistance of the sintered for 90 minutes were clearly improved. The test piece was tested in a 3.5% NaCl aqueous solution. The test results are shown in Table 3. The corrosion current density of the coated alumina test strips decreased significantly, and the pitting potential (compared to the calomel reference electrode) increased significantly. The test strips were blinded in the atmosphere of 90 ° (rc • ίΐίΐ The test, as shown in Fig. 3, shows the oxidation resistance of the coated oxidized test piece. The pore corrosion potential (V) is 855. 0.25. Test piece type Corrosion current density (/ zA / cm2) MAR-M247 Substrate 13.5 Coating oxidation Aluminum test piece 1.7

Claims (1)

574414、 六、申請專利範圍 (e)刚述（b)之燒結溫度是以室溫升溫到T0(80oC〜120。〇 保持值溫t〇(5分鐘〜15分鐘），再升溫至ti(2〇〇〇C 350C)保持怪溫fi(5分鐘〜15分鐘），再升溫至T2 最後 (4〇〇°C〜480°C)保持恆溫t2(5分鐘至15分鐘）， 再升溫至T3(450〇C〜1〇〇〇。〇仅4± t 保持恆溫t3(20分鐘 180分鐘） 發明名稱 中文 Α1ζ〇3陶瓷膜饭復於MAK4J24Y超合金之電鉍方法 ........................ 英文 Ceramic ⑽职0η 刪247 S聯rall〇y 發明人 (共2人） 姓名 (中文） 1·顏秀崗 2.奋至若 姓名 (英文） l.Shiow-Kang Yen 2,Cheng~Chun Chang 國籍 (中英文) 1·中華民國ROC 2.中華民國R〇C 住居所 (中文) 1·台中市南和路213號16F-2 2·台中市台中港路三段35-1號 住居所 (英文) 1. 2. 申請人 (共2人） 名稱或 姓名 (中文） 1·顏秀崗 __ 1 _ 2.張正君 名稱或 姓名 (英文） l.Shiow-Kang Yen — 2.Cheng-Chun Chang 國籍 (中英文) 1.中華民國ROC 2.中華民國ROC 住居所 (營業所) (中文) 1·台中市南和路Z13號卜〈尽地址與前向眚A申缚去；κ同、 2.台中市台中港路三段35_1號（本地 住居所 (營業所) (英文) 1. ........ 2· 代表人 (中文） 1. 顏秀崗 .........___—...... 2. 代表人 (英文） l.Shiow-Kang Yen 2·574414, VI. Patent application scope (e) Just stated (b) The sintering temperature is to raise the room temperature to T0 (80oC ~ 120 °), maintain the temperature t0 (5 minutes to 15 minutes), and then raise the temperature to ti (2 〇〇〇C 350C) keep the strange temperature fi (5 minutes ~ 15 minutes), and then raise the temperature to T2 Finally (400 ° C ~ 480 ° C) keep the constant temperature t2 (5 minutes to 15 minutes), and then raise the temperature to T3 ( 450〇C ～ １０〇〇〇〇 Only 4 ± t keep constant temperature t3 (20 minutes 180 minutes) Invention name Chinese A1ζ〇3 ceramic film rice in MAK4J24Y superalloy electric bismuth method ......... ............... English Ceramic Die 0η Delete 247 S 联 rall〇y Inventor (Total 2) Name (Chinese) 1. Yan Xiugang 2. Fen Zhiruo Name (English) l. Shiow-Kang Yen 2, Cheng ~ Chun Chang Nationality (Chinese and English) 1. ROC ROC 2. ROC Residence (Chinese) 1. · Taichung City, Nanhe Road 213 16F-2 2 · Taichung City Residence at No. 35-1, Section 3, Taichung Gang Road (English) 1. 2. Name of applicant (2 persons) or name (Chinese) 1. Yan Xiugang __ 1 _ 2. Name or name of Zhang Zhengjun (English) l.Shiow -Kang Yen — 2.Cheng-Chun Chang Nationality (Chinese and English) 1. ROC ROC 2. ROC Residence (Business Office) (Chinese) 1 · No. Z13, Nanhe Road, Taichung City 〈Declaration of address and forward to 眚 A; κDong, 2 .No. 35_1, Section 3, Taichung Port Road, Taichung City (Local Residence (Business Office) (English) 1. ........ 2 · Representative (Chinese) 1. Yan Xiugang ......... ___—...... 2. Representative (English) l.Shiow-Kang Yen 2 · 第1頁page 1 574414 圓式簡單說明 .......:......... 圖一製程步驟示意圖 圓二 燒結過程示意圖 圖三 試片於900 °C大氣中進行8小時恆溫氧化試驗之熱重 分析（TGA)圖574414 Round type simple explanation .......: ......... Figure 1 Schematic diagram of the process steps Circle 2 Sintering process diagram Figure 3 The test piece is subjected to a constant temperature oxidation test at 900 ° C for 8 hours. Reanalysis (TGA) plot 第11頁Page 11 574414； —本 六、^請奉科範固 利 1· 一種形成氧化鋁陶瓷鍍層於基材上的製程，其方法是 用電解沉積鍍液中電解沉積氧化鋁於基材上： (a) 基材是MAR-M247超合金， (b) 方法步驟為： (1) 前處理 (2) 電解沉積 (3) 乾燥 (4) 燒結 (c) 前述（b)之電解沉積鍍液是Α1(Ν〇3)3水溶液，其濃度 範為是從〇·1Μ至0.001M。 (d) 前述（C)之電解沉積電鍵為恆定電位其範圍*7〇〇mV 至1 500mV相對於飽合氣化銀電極。574414; Ben VI, Fenke Fanguli 1. A process for forming an alumina ceramic coating on a substrate, the method of which is to electrolytically deposit alumina on the substrate using an electrolytic deposition bath: (a) base The material is MAR-M247 superalloy. (B) The method steps are: (1) pretreatment (2) electrolytic deposition (3) drying (4) sintering (c) the electrolytic deposition plating solution of (b) above is Α1 (Ν〇 3) 3 aqueous solution, whose concentration range is from 0.1M to 0.001M. (d) The electrodeposited electrode of (C) above is a constant potential with a range of * 700 mV to 1,500 mV relative to a saturated gasified silver electrode. WW