MATERIALS AND ENERGY BALANCES DEVELOPMENT FOR THE NI-W ALLOY ELECTRODEPOSITION PROCESS AT DIFFERENT TECHNOLOGICAL PARAMETERS

Size: px

Start display at page:

Download "MATERIALS AND ENERGY BALANCES DEVELOPMENT FOR THE NI-W ALLOY ELECTRODEPOSITION PROCESS AT DIFFERENT TECHNOLOGICAL PARAMETERS"

Bertha Richard
6 years ago
Views:

1 , Brno, Cech Republc, EU ATERIALS AND ENERGY BALANCES DEVELOPENT OR THE NI- ALLOY ELECTRODEPOSITION PROCESS AT DIERENT TECHNOLOGICAL PARAETERS ara POROCH-SERITAN*, Sona GUTT*, Gheorghe GUTT*, Traan Lucan SEVERIN* * Ştefan cel are Unversty of Suceava, Unversty Street, Nr. 3, 75, Suceava, Roana, E-al: arap@fa.usv.ro, gutts@fa.usv.ro, g.gutt@fa.usv.ro, severn.traan@f.usv.ro Abstract The paper presents the results acheved on the correlaton of between the separated quanttes of substances at the two electrodes of a galvanc wth the current effcency, ntensty and operatonal tes, takng nto account the ntal coposton of the electrodeposton bath of the - alloy at dfferent technologcal paraeters such as current densty, teperature, ph. Energy dspersve spectroetry (EDS) was further used n order to deterne the checal coposton of the - coatngs for varous platng current effcences calculaton. As the current densty ncreases, the current effcency decreases and the wolfra content reans constant about % at current denstes of A/c and 6 A/c respectvely. Accordng to our fndngs, the tungsten and nckel contents and also the output current ncrease wth teperature. hen the ph value ncreases fro 7 to 8, the wolfra content rses fro 3.5 wt.% to.65 wt.%, the sae behavour could be observed for the current effcency. Another goal of our study was to nvestgate the ateral and the energy balances of the electrodeposton process of - alloy. The startng pont s the theoretcal aterals balances. The real ateral balance s obtaned after a seres of experents at dfferent technologcal paraeters values. In all the cases, the ateral and the energy balances respectvely are found to be affected by technologcal paraeters, consequently havng an nfluence on the ateral and, respectvely, specfc energy consuptons, ndcatng, n ths way, the possblty of acton n order to explot energy n a useful purpose as uch as possble. Keywords: - alloys, electrodeposton, balance, aterals, energy. INTRODUCTION The nckel tungsten ( ) alloys exhbt exent corroson resstance [], [], [3], wear resstance, hgh hardness and agnetc propertes [], [5], so the nterest n ther electrodeposton has ncreased n recent years. It was reported that the hardness of alloys s three tes hgher than that of pure electrodeposted [6]. The present research focuses on the developng of the theoretcal foundatons of ateral and energy balances for the electrolytc deposton of - alloy and the nfluence of process paraeters (current densty, teperature and ph) on the real balance of aterals and energy. The startng pont s the theoretcal aterals balances. The real ateral balance s obtaned after a seres of experents at dfferent technologcal paraeters values.. EXPERIENTAL ckel tungsten alloys were electroplated fro aqueous solutons contanng 6.86 [g L - ] 6H O (nckel sulphate hexahydrate, Sga - Aldrch) and 3.9 [g L - ] Na O H O (sodu tungstate dhydrate, Sga - Aldrch) as the electro actve speces, and 7. [g L - ] C 6 H 5 Na 3 O 7 H O (tr-sodu ctrate dhydrate, Sga - Aldrch) as the coplexng agent [7]. The classcal electrochecal was equpped wth a cathode (ade of % purty copper) and a carbon anode. The cathode densons are of 8. c (heght), 9.8 c (length), and dth) whle the densons of anode were of 6. c (heght), and respectvely the anodc erson surface was of.5 d. Before electrodeposton, the electrode surface was polshed wth eery paper (3 gran se), then was had wth dstlled water, thoroughly degreased wth acetone, actvated wth % H SO, washed once ore wth dstlled water and erse n the bath soluton. The above descrbed was connected to the GINSTEK GPR-8HD power supply, havng a dgtal control of current and voltage. The tested condtons are gven n Table. The cathode current effcency ( ) was calculated takng n consderaton the weght of the depost obtaned experental

2 , Brno, Cech Republc, EU ( ) p and the theoretcal weght deterned fro araday's law ( ): ( t p ) t (.) The approxate coposton of the alloy deposts was deterne wth a scannng electron croscope (SE, VEGA II LU - Tescan, Cech Republc) and the attached energy dspersve spectroscopy (EDS, Bruker AXS croanalyss GbH probe). Each saple was easured n three dfferent locatons to confr unforty. Table.. Technologcal paraeters used n the electrodeposton of - alloy Technologcal paraeters Saple No., T, [A/c ph ] [ºC] RESULTS AND DISCUSSION 3.. aterals balances n cathodc copartent for the electrochecal - alloys Eq. reveals the stochoetrc equaton of the process of electrodeposton process of - alloys for cathodc copartent at stable coposton: NaO HO 8e 8 Na SO (.) To express the quanttatve stage of the electroplatng bath at a gven te one ay use the transforaton Na O degrees of the coponent of nterest ( ) or of any other coponent ( ) [8] [9]. In the present study the transforaton degree of the coponent of nterest ( ) was calculated accordng to Eq 3., where: - ntal ass of reactant ( =, Na O, H O,,, Na SO ), [g] - ass of reactant at a gven te, [g]; - atoc ass of reactant; - stochoetrc rato of reactants. NaO NaO NaO NaO NaSO NaSO H O NaSO NaSO (3.) The aount of each coponent at a gven te ay be calculated wth the fallowng balance equatons [8]:

3 , Brno, Cech Republc, EU (.) NaO NaO NaO NaO NaO NaO (5.) H O (6.) e (7.) (8.) NaSO NaSO NaSO 8 NaSO (9.) or the galvanc processes, the use of current effcency ( current ) nstead of the degree of transforaton [8] [9] s ore useful. In ths case, t s desred to acheve hgher current effcency for the reacton product of nterest (- alloy):, real,, theoretcal % %, theoretcal I % %, real I current, (.), where: - atoc ass of coponent, [g]; - atoc ass of coponent, [g]; - tes of deposton, [s]; - current effcency of - alloy; I - current ntensty, [A]; - araday s nuber ( = 965 C); - valence; - (VI) valence; %, % - percentages of nckel and tungsten respectve n the depost. ro equatons (7.) and (.) the transforaton degree ( ) ay be calculated. The stochoetrc equaton of the electrodeposton process for the - alloys, n the cathodc copartent s: % % I % % I current, (.) 6 I Substtutng the degree of transforaton n each cathode copartent balance equaton wth eq. (.), we obtan the followng theoretcal balance equatons: I (.) Na O I Na O Na O (3.) I H O (.) I current, (5.) 3

4 Coponent quantty , Brno, Cech Republc, EU I 8 (6.) Na SO I Na SO (7.) Based on relatons (), (3), (5) and (7) the nuercal values of the theoretc and real ateral balances for the cathodc copartent durng the - alloys electrodeposton processes were acheved and are shown n gure. Instead of transforaton degree, the current effcency was used n our calculatons, beng consdered % for the theoretcal ateral balance and the experental values for the real one. [g l-] entered NaO [g l-] entered [g l-] out theoretcally NaO [g l-] out theoretcally [g] teoretc NaSO [g l-] out theoretcally [g l-] out real NaO [g l-] out real [g] real NaSO [g l-] out real 8 6 [g l-] entered NaO [g l-] entered [g l-] out theoretcally NaO [g l-] out theoretcally [g] teoretc NaSO [g l-] out theoretcally aterals [g l-] out real NaO [g l-] out real [g] real NaSO [g l-] out real Saple No. 3 g.. Theoretc and real balances for the cathodc copartent durng the electrodeposton of - alloys at the studed operatonal paraeters (Table ) 3.. Influence of technologcal paraeters on current effcency and tungsten content It was noted fro the results obtaned and used to calculate the ateral and energy balances that the current effcency decreased wth the current densty ncrease and the tungsten content reaned constant at around wt.% for the current denstes of A / c and of 6 A/c respectvely. Krshnan and hs collaborators also presented n ther work [] a decrease n the current effcency wth the ncreasng of the current densty. The sae results showed that the tungsten and, respectvely, nckel content as well as the current effcency ncreases wth the ncreasng of teperature, whle the ph of the bath has a sgnfcant effect on current effcency as well as on the tungsten content n the depost. or exaple, ph ncreased fro 6.78 to 8 ncreases the tungsten content fro 3.5% to.65% and, at the sae te, the current effcency ncreases. A further ncrease n ph fro 8 to 9.3 causes a decrease n both the current effcency, and the content of tungsten and nckel, respectvely. Krshnan and hs collaborators [] also showed an ncrease n the current effcency wth the ncreasng of teperature, whle Yaasak and collaborators [] descrbed the effects of teperature on both the tungsten content and the ductlty of the depost. Atanassova and collaborators [] have observed an ncrease of the tungsten content wth the ncreasng of teperature n both the baths wthout agtaton and those wth agtaton and put ths behavor on the condtons that encourage the transport of tungsten towards the cathode surface The energy balance for cathode copartent n the electrodeposton of - alloys or the deternaton of the specfc energy consupton per ass unt of - alloy cathode the expressons of electrcty n an electrcal crcut wth resstve consuer and the ateral balance for any coponent (n ths case - alloy depost) are consdered [8] [9]: % % I current, (8.)

5 Specfc energy consupton [J g - ] , Brno, Cech Republc, EU Consderng that the specfc energy s expressed as: U I, (9.) sp The specfc energy ( ) for any coponent ay be calculated as: sp U % % (.) where: sp - specfc energy, [J/kg]; U equatons the energy balance for the electrodeposton of - alloys s: - voltage appled, [V]. Based on ateral balance and the prevous U I I (.) U I (.) Na O Na O Na O I U I I (3.) U % % (.) U (5.) 8 I U (6.) Na SO Na SO I e Based on the actual ateral balances for the electrodeposton processes of - alloys at varous technologcal paraeters (Table ) and on the relatons (8.) (6.) real energy balances were developed for the coponents of the cathodc copartent (gure ). sp [J g-] sp NaO [J g-] sp [J g-] sp NaSO [J g-] sp total cathodc copartent [J g-],,8,6,, sp total cathodc copartent [J g-] sp NaSO [J g-] sp [J g-] sp NaO [J g-] sp [J g-] Saple No. g.. The real energy balance for cathode copartent at the electrodeposton of - alloys (Table ). 5

6 , Brno, Cech Republc, EU. CONCLUSIONS The developent of ateral and energy balances for the actve speces present durng the - alloy cathodc electrodeposton proves the effcency of galvanc processes at dfferent operatonal paraeters. As the current densty ncreases, the current effcency decreases and the wolfra content reans constant about % at current denstes of A/c and 6 A/c respectvely. Accordng to our fndngs, the tungsten and nckel contents and also the output current ncrease wth teperature. hen the ph value ncreases fro 7 to 8, the wolfra content rses fro 3.5 wt.% to.65 wt.%, and the sae behavour could be observed for the current effcency ncreent. In all the cases, the ateral and the energy balances respectvely are found to be affected by technologcal paraeters, consequently havng an nfluence on the ateral and, respectvely, specfc energy consuptons, ndcatng, n ths way, the possblty of acton n order to explot energy n a useful purpose as uch as possble. Research wll contnue to opte the process of electrodeposton of - alloy n relaton to techncal and econoc crtera. REERENCE [] - OBRADOVIC., STEVANOVIC J., DESPIC A., STEVANOVIC R., STOCH J., Characteraton and corroson propertes of the electrodeposted alloy, J. Serb. Che. Soc., 66,, p , ISSN: [] - OBRADOVIC., STEVANOVIC J., DESPIC A.R., STEVANOVIC R., Electrochecal Deposton and Phase Structure of Electrodeposted - Alloys, J. Serb. Che. Soc., 6, 999, p. 5 57, ISSN: [3] - GABE D.R., The role of hydrogen n etal electrodeposton processes, J. Appl. Electroche., 7(8), 997, p , ISSN: (electronc verson) [] - YAASAKI T., SCHLOSSACHER P., EHRLICH K., OGINOI Y., oraton of aorphous electrodeposted - alloys and ther nanocrystallaton, Nano-Struct. ater.,, 998, p , ISSN [5] - YAASAKI T., Hgh-strength nanocrystallne alloys produced by electrodeposton and ther ebrttleent behavours durng gran growth, Scrpta aterala, (8 9),, p. 97 5, ISSN: [6] - LOE H., EHRELD., DIEBEL J., Ultraprecson croelectroforng of etals and etal alloys, Proc. SPIE, 33, 997, p , ISSN: 9-386, E-ISSN: [7] - ELIAZ N., SRIDHAR T.., GILEADI E., Synthess and characteraton of nckel tungsten alloys by electrodeposton, Electrochca Acta, 5, 5, p , ISSN: [8] - GUTT S., GUTT Gh., Contrbut asupra blantulu de aterale s energetc la ascutrea electrochca, Revsta de Che, (), 993, p , ISSN: [9] - GUTT S., GUTT Gh.; Contrbut la stablrea blantulu de aterale s energetc pentru procesul de nchelare electrochca cu convecte ultrasonora, Revsta de Che, 6(8), 997, p. 5 53, ISSN: [] - KRISHNAN R.., JOSEPH KENNEDY C., JAYAKRISHNAN S., SRIVEERARAGHAVAN S., NATARAJAN S.R., VENKATAKRISHNAN P.G., Electrodeposton of nckel-tungsten alloys, et. nsh., 93(7), 995, p. 33, ISSN: (electronc): [] - YAASAKI T., TOIRA R., OGINO Y., SCHLOSSACHER P., EHRLICH K., oraton of Ductle Aorphous & Nanocrystallne - Alloys by Electrodeposton, Plat. Surf. nsh., 87(5),, p.8 5, ISSN: [] - ATANASSOV N., GENCHEVA K., BRATOEVA., Propertes of ckel-tungsten Alloys Electrodeposted fro Sulfaate Electrolytes, Platng & Surface nshng, 8(), 997, 67, ISSN:

Standard Electromotive Force (EMF) Series. Outline. Concentration and Temperature Effects. Example

Standard Electromotive Force (EMF) Series. Outline. Concentration and Temperature Effects. Example Standard Electromotve Force (EMF) Seres Outlne Bref Revew: Corroson Concentraton and Temperature Effects Example Corroson Rates Polarzaton Corroson Rate - Actvaton - Concentraton Passve behavour For any