CA1183488A - Process for the electrodeposition of ferro-nickel alloys - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process of electrodepositing on a substrate a layer of ferro-nickel alloy, using as a soluble anode an anodic basket which is filled with granules of ferro-nickel having a structure which is basaltic or is equi-axed without a dentritic substructure and having a composition, by weight,of:
nickel, with or without cobalt impurity, 20% to 90%;
not more than 1% and not less than 0.1% in total of silicon, manganese, magnesium, aluminum and calcium;
iron, the remainder of the composition.

Description

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rhe :Lnvention relates to a process ~or the el~trod~posl-tlon oE ~ron-nickel alloys.
Our earlier U.K, patent speciEicaLion No. 1,552,837, here-inafter called the "Parent Patent", ~corresponding to our French specification No. 2,320,996) claims a process of electrodeposi-tion a layer of ferro-nl~ckel allo~ using as a soluble anode an anodic basket (subsequently referred to as a "panode"~ fllled with granules of ~erro-nickel ~hich are ductile when rrushed~ have been made by pouring molten metal into a bath of water, and have a composition such that their iron~nickel ratio is substantially identical to that of the layer which it is desired to deposit.
The earlier specification states that the teaching relating to those ferro-nickels whose nickel content is from 73 to 77% by weight is applicable to ferro-nickels having a nickel content of from 20 to gO%. The specification says that cobalt may be present in amounts which can reach several percent by weight.
The present invention has arisen from a study of the application of the process of our earlier specification to ferro-nickels ~nose nickel content is between 20 and 60%.
During the studies leading up to this invention, it was found that in order to produce low sludge ratios it is advantage-ous to provide the panodes with granules~ the structure of which is basaltic or equiaxed without a dendritic sub-structure .~

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prod-~ced by in~er-dendrltlc seEre~ation. ~h~ ~article joints ~re flne. The bnsaltlc structure giV~3 bet~er resul~s than those obtained with equlnxed ~ructure :~artlcles~ The dlmen~ion o~ the particles (the msJor diameter) 18 pre~er~bly between l and l5 mm.
For R derinition Or ba3altic and e~uiaxed structure3 re~erence should be oade to "Uetals handbook Volume 8 - ~etallography, structures snd phnse diagrams" publi3hed by "The American Society ior ~etals" ~nd -~ "A conci3e encyclopedia oi metallo~raphy" by A.D. ~erriman, publ'shed by Elsevir Publi~hing Company - Amsterdam - 1965 - page l~l.

Aqua regia a9 deilned in US Standard AST~ E 407-70 Nm. 12, may be u~ed to show the structure oi the granules ~nd the iollowing reagent ~ay be used to show the particle sub-~tructure:
400 ml Ha ~density _ 1.2 8 ~ ~uCl2 28 g FeC13 20 ml HN03 (density = l.4) 800 ml methanol ~100 ~1l H20 .
Since it ls diiiicult to determine qunntltatively whether a str~cture i~ basaltic or equiRxed with or without a dendritic sub~tructure, a test hàs been perrected whereby it is possible to tell 3~

by means of a simple h~nd-vice to tell whether a batch of granules gi~2s a high sludge ratio. The test compri~es ~imply subjecting to 3 compression test between the jaw9 of a h~nd-vice a sample of granule~ with a size of preferably between 10 and 15 mm.
If the granules ~ubjected to this test do not disintegrate under 8 compression which reduces their major diameter by at least one-third, and if the qum of the adjuvants and impurities does not e~ceed 150, the slud&e ratio may be expected to be less tha~
1.5~u. ~he test carried out by the a~erage per30n i9 equivale~t to 8 Gompr3sqion test of about 2 to 2.5 tonnes.
~ o~e~er, since this test i9 only semi-qusntstati~e, a ~ew test ~as perfected using a compression machine. If the granule~
do not disinte~rate under a compreqsion of 5 tonnes, ~nd if the sum of the sdjuvants and of th~ impurities is not mor~ than l~o~
the sludge ratio nill b~ less than l~o- If the first crack does not appear until a value above 2 tonnes, ~nd if the sum of .~, the adjuvants and of the impurities does not e~ceed 0. ~5~ the sludge ratio will be less than 0.510.

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~ 4 -These compressinn tests w~re carrled nut wLth gr~nules, each ma~or diame~er end o~ ~hich ~as Eormed ~:Lth a ~lat oE an area of about 15 mm2. Compression tests of th~s kind give a deformation value- ~ e as a funceion of the load applied. From the discontinuities found on this curve it is possible to measure with fairly good accuracy the values corresponding to disintegra-tion and to first cracking. This eest is a fairly reliable means of determining the sludge ratio. Obviously the test should be carried out on a representative sample of the batch of granules intended for use for electroplating.
Thus the present invention provides a process of electro-depositing on a substrate a layer of ferro-nickel alloy, wherein there ls used as a soluble anode an anodic basket which is filled ~ith granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dendritic substructure and are of the composition by weighe:
nickel, with or withoue cobalt impurity, ?0 to 90~;
not more than 1% and not less than 0.1% in total of silicon, man~anese, magnesium, alu~inu~ and calcium, the ranges for these elements being selected from the g~oup consisting of !
silicon 0,Q2 to 0.5%
carbon 0.~3 to 0.2%
magnesium 0.02 to 0.4%
manganese 0.01 to 0.1%
aluminum 0.01 to 0.1%;
and silicon 0.04 to 0.2~
carbon 0.03 to 0.1%
magnesium 0.02 to 0.1~
manganese 0.01 to 0.67 aluminum 0.01 to 0.06%;
and silicon 0.04 to 0.1%
carbon 0~03 to 0.05%
magnesium 0~02 to 0~08 manganese traces aluminum traces;
and not more than 0.2% of other ~mpurieies;
iron, the remainder of the composition. The ranges of the additive elements are given with an inaccuracy of 0.01% and the ranges of the sums are gi~en ~i~th an inaccuracy of 0.0~%.
The present inventl~n also provi~es a process of electro~
depositing on a substrate a layer of ferro-nickel alloy, wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-ni~ckel which have a structure which i~s basaltic or is equi-axed without a dendri~tic substructure and are of the composition by weight~

nickel, with or uithout coBalt impurity, ~0 to 90%;
not more than 0.3% and not less tfian 0.2% in total of silicon, manganese, ~agnesi~m, aluminum and calcium, these ~i~e elements being within the ranges:
silicon 0.04 to 0.27, carbon 0.03 to 0~1%

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- 4b -magnes~ 0.02 to 0~1 manganese 0.01 to 0.6 alwmim~ O.01 to 0.06%~
and not more than 0,2X of other impurities;
iron, the remainder of the composition.
The present invention also provides a process of electro-depositing on a substrate a layer of Eerro-nickel alloy, wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dentritic substructure and are of the composition by weight:

nickel, with or w~thout ccbalt impuri~ty~ 70 to 80%;
not more than 1% and not 12ss than 0.1% i~n total of silicon, manga~nese., magnes.~um~ alumi~nu~ and calci~m, these ~ive eleme~ts~b-ein~ w~th~n thè ranges:
sili~con 0.04 to U.1%
carbon 0~03 to 0~05%
magnesi~m 0.02 to 0.~8%
manganese traces al~mi~um traces, and not ~ore than 0.2% of other impurities;
iron, the remainder of the c~mposition.
The present invention al$o provides a process of electro~
depositing on a substrate a layer of ferro-nickel alloy, where~n there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dentritic substructure and are of the co~position by weight:

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~ !I C ~
ni~ckel, ~ith Or w:lthout ~obslt ~mpurlty, 50 to 70X;
not m~re than 1~ ~nd not le~s than 0~1% in total of si~licQn, manganesa, magnasium, alumln~ and calcium, these fi~e elem~nts ~eing ~ithi~ the ranges:
silicon 0.1 to 0.2%
carbon 0,03 to a~l%
ma~nesium 0.03 to 0~08%
manganese 0.01 to 0.08%
aluminum 0,02 to 0,06%, and not more than 0.2% of other impurities;
iron, the remainder of the composition.
The present invention also provi~des a process of electrodepositing on a substrate a layer of ferro-nickel allo~, wherein there is used as a soluble anode an anodic basket ~hich is filled with granules of ferro-nickel which have a structure uhich is basalt$c or is equi~axed without a dendritic substruceure and are of the composition by weight:
nickel, with or without cobalt ~mpurity, 20 to 90%;
not more than 1% and not less than 0.1% in total of silicon, manganese, aluminum and calcium, these five elements being within the ranges:
silicon 0.02 to 0.5%
carbon 0.03 to 0.2%
magnesium 0.02 to 0.4%
manganese 0.01 to 0.1%
aluminum 0.01 to 0.1%, and not more than 0.2% of other impurities;
iron, the remainder of the compos~tion.

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The r3nges of thP addltive elements given tor the above processes have ~n inaccuracy of 0.01~ and the ranges of the sums have an inaccuracy of 0.02X.

The chloride ion content in the electrodeposition bath may be between 10 and 40 grams per litre, in a preferred embodiment.
During the study leading up to this application it ~as found that granules containing sllic~n and at least two ad~uvants selected from the grpup comprising manganese, magnesium, alumin-ium and carbon, in ~he following respective proportions:
Silicon : from 0.02 eo 0.5%
Carbon : from 0.03 to 0.2%
~agnesi~um : from 0.02 to 0.4%
Manganese : from 0.01 to 0.1%
Aluminium : from Q.01 to 0.1%
give sludge ratios less than 1% if the sum of the v~rious adjuvants meets the following requirements; ~hen the granules with which the panodes are provided are of a composition such that the mass ratio of nickel plus cobalt to ~ron plus nlckel plus cobalt is between 0.20 and 0.50, the sum of the adjuvants contained in the granules must be between 0.1 and 1%; when the granules with which the panodes are provided are of a composition such that the mass ratio of nickel plus cobalt to iron plus nickel plus cobalt is between 0.50 and 0.70, the sum of the adjuvants must be between 0.2 and 1%; when the granules with which the panodes are provided are of a composition such that the mass ratio o~ nicke~ ?lu~ cobnLt to lron l-lu~ nick~l plu~ cobalt i3 b~t~ n ().70 nnd n. ~o ~ the ~u~ of the adjuvnnt3 must be between 0.1 ancl 1~,.
Præferab.ly, the sum o~ the magne~lu~, mnngane~e an~ alumlnium oontnined in the ~nule3 13 nt least 0.05~.
~ o obtnln a 31ud~e rntio less eh~n O.S~0, the pQnodes nre adv~ntngeou31y provlded ~lth granules whlch cont ~ n slllcon nnd at leaet t~o other adjuY~nt~ ~elected irom the ~roup co~prislD6 ~ngane1e, ~agnesiUQ~ alumlniuQ and c~rbon ln the ~ollo~ing respective proportlons:
Silicon : irom 0.04 to 0.2~o Carbon ; ~rom 0.03 to o.lZ
Yagne~ium : ~rom 0.02 to O~l~o ~ anganese : irom 0.01 to 0. 6~o Alumlnium : irom 0.01 to 0.06~.
The sum o~ the sdJuvants present in the grsnule~ must be bet~een 0.2 and 0.3~.
Preierably, the 8UQ Or the ~agnesium, manganese and alum1nlum contained in the granules ls batween 0.07 and 0.2%. The top ~alue oi the ranga is ~e~i~e-only to the extent that it is requirsd to keep the concentration oi these metal~ ~t lo~ level~9 Advants&eou3lyi lf the mass ratio oi nickel plus cobalt to nickel plus lron plus/cob~lt in the ierro-nickel~ i8 bet7een 0.70 and 0.80, the preierred range3 are as iollow~:
Sillcon : i'rom 0,04 to O~l~o Carbon : irom 0.o3to 0.050 Yagnesiu~ : irom 0.02 to 0~087 ~anganese : traces Alumini~m : traces In the case oi ierro-nickels whose mass ratio of nickel p'us cobalt to iron plu9 nickel plus cob~lt is between 0.50 and 0.70, the preferre~

range0 nr~ a~ rOllO~a:
Sillcon . rrom O.l to 0.2 C~rbon : rrom 0.03 to 0.1~
Y~gn~sium : rrom 0.03 to 0.08S
~anganese : irom 0.01 to 0.0~%
Alu~inium : irom 0.02 to 0.0670 The Yalues of the range9 are given ~ith an indetermination Or the order o~ 0.01~ ~or the individual ranges and 0.02~ ~or the sum r~nges.
At this polrt ~t should be noted that the quality o~ the metal coatlng produced by electropl~ting dependY very ~uch on the ratio bet~een the ~erric ions nnd the total amDunt o~ iron di~sol~ed in the electrolyte. I~ this ratio i9 very high, the deposit contains iron hydroxide which occurs in the ~orm of numerous spots of rust colour.
I~ the iron ~tabilizer i~ a com?lexing agent, as i~ the case in the ex~ples, thls ratio ~hould not be re than 0.40,nnd ia preferably le~s than 0.20. It i8 very di~ficult to kee~ the ratio in~ide the above-lndicated limit~ and the ratio is generally around 0 50 The proce~s accordlng to this invention solves this nroblem.
The ratio bet~een the rerric iron and the total quantity of iron diY301~ed in the electrolyte can be ke?t at about the preferred limit~, simply by using ierro-nickel granules. I~deed none of the numerous meas-~rements Or this rstlo taken hltherto has exceeded 0.20.
Another iactor ~hich lnfluences the quality Or the cathode coatlng is the cleanness and the porosity Or the anodic sac~ ~hich aurround the anodes ar,d which retain the ~ludges, which would other-wise rall to the bottom of the tank. Unless these anodic sacs are changed frequently, the cathodic coating may ~ue a ~ery irregular thickness. This problem is particularly acute when small quantities of sul?hur are added to the nicke~ anodes to racilitate dissolution.

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? Thi9 problem appenr3 ~o be ~olYed sl~aly by u~ing rerro-nlc~e granules ~,ccording to tha 1n~ntion, slnce lt hn~ never b~en cet ln numerous testa c~rrled out wlth terro-nick~l Fr~,nule~.
Flnally, th,e ~erro-Dickel grnnules ar~ highly soluble nnd thl~
hlgh solubllity means thnt there 19 no need to u~e solubill~er~, and the amount o~ chlorid~ ion~ in the electrolyte can be reduced to a ~nlue o~ between 10 a~,d 40 g per lltre.
The use o~ ferro-nickel granule~ also enable~ bath3 to be used wl~h a sulphate ~on to chloride ion concentration ratio ot between

2.~ nnd 4 expr~s~ed as g per lltre.
The ~ollowing ~on-llmitatlve examples are in~nnded to enable the skllled sddressee readlly to determine the operatlng conditlon3 ..
adYantageously used ror each 3pecl~ic case.
,~, Exsmple 1 A batch o~ granules having tbe following co~positlon:
Nickel : 76.7 ~ Cobalt 0.50 .. .
Sllicon : 0.13 Carbon O.O
Sulphur : 0~01~
Iron : to make up to lO0~, ~as u~ed to carry out a test in an 80 litre electrolytic tank containing the same electrolyte as that descrlbed in Exa~,ple 6 in the Parent Patent~ at a temperature Or ~0 C ~ith air agitation.
This tèst ~ continuoualy carrled out ior2200 hours with a current den~ity o~ 2.5 amps per squnre decimetre, corresponding to n total curren* o~ lO9 000 amps per hour. The panode ch~rge had to be rene~ed rour tlmes ior thi~ te~t, ~- The results obtained were ns iollows:

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Sludge ratlo 0.9~.; ratlo Or lron llI to tot~ lron ~n~ c~na~nnt betwe~n 1` ancl ~0 E.~am~le 2 Another tcst ~a~ cnrrled out ln a ~S00 litre tank u~ing the sQme granules and th~ ~3me electrolyte a8 ln Example 1, with n pH
o~ 3.2 and a temperature o~ 60 C, agl~tion being carried out mechanically.
The te~t ~as carrled out lntermittently ~or a pariod Or 8 ~onths ~ith ~ current density r~nglng ~rom 0~ to 3 amperes per square dm corresponding to a current o~ about 500 000 amps per hour.
The result~ were as iollow3: ~he Fe III: total iron ratlo ke?t constsnt bet~een 2 ancl 9$; the sludge ratlo ~as negligible.
No proble~ ~a~ ~ound tunllke the technlques u~ed ln the prior art~ ~nd aiter the panode charge had been con3umed and rene~ed there 7a8 no n~d to clean the panodes~the anodic sacs or the anodlc cells.
Example~ 3 to 29 Example8 3 to 2~ ~ere carrled out ln the ~ame ~ay sa 1~ Exa~ple~
1 and 2, the te3ts lasting ~or sbout 200 hours ~ith a current density o~ about ~ ~mpQras per s~uare dm with the ~me bath ag that used ln Example G o~ the Parent Patent.
The ~ame sample9 oi granules uere also tested ln a bath having the same mlneral constltuent~ but wlth the ~ollowing organic compound~:
Sodium ~accharinate : 5 g per litre 1,3~6-na~hthslene -trisulphonlc acid : ~ g per litre A~corblc acld : 0.3~ g per lltre Sodium lauryl sulphate : 1 cc per litre The anode yleld ~a~ o~ the ordQr o~ 10070. The cathode yield ~a~ o~ the order oi 9~. The quality o~ the coatlng ~as excellent ~nd identical to that obtained with the bath Yimilar to that o~
Example 6 of the Parcnt Patent.

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Tne te~t~ corre~pondln~ to Exnmplen 23 to 29 were cnrrlcd out under the an~e condltlona ns ln the prevlous E.Yn~PL~9 ~Ut becnuac o~
the sm~ lze o~ the electroly~i~ cell th~ee testn wer~ only dissolution te~t~ nnd not cnthodie de~oaltion tedt~.
The results corre~pondinF to Examples 3 to ~9 ~re ~hown in the ~ollo~hg Table.

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~ . ~11~34~8 Tablc ~ I - Analysig 0~ granUles ~ by ~eiæht) Ni ! Co ! Si l ~ J _ S ~Sl ~
!76,5!0,4U!0,05~!0,0035~!traces!tr~ces~!0,00~ !0,0110 ! o à 7 ~ !l n7 1 o, 0157 ! ! ! _ ! _ ~ ! _ ~ !76,6!0,SO!n,12~!0,~0~5~!tr~ces!trac~s !O,OG3 !0,0110 ! S,~
y I ! _ !0,22 !O.OlS7 ! ! ! ! _ !75 ~!0,50!0,10~!0,0035à!traces!traces !0,003 !C,OllO !3,5 à 7 ~76 1 ~0 oO !0 0157 !
_` ` _ ` ~ ! _ _ 6 !76 à!O,55!0,05~!0,005 ~!traces!< 0,05 !0,002 !O,OlOOà!2,5 à 5 !77 ! !0,20 !~ 0~020! ~ 0,0120 ! __ _ 7 176,5l0,49!0~38 ! 0,11 !traces!< O,OS !traces!O,OllO ! 5 8 176,5!0,49!C,Oo !traces !traces!traces !0!05 10,0100 ! 6 ~ 7 9 !76,3!0t47!0,}2 ! 0,025 !traces!traces !traces!O,O~O ! 2,1 10 !75 !014~!<0!05!traces ! 0,05 !< 0,05 !traces!0!0100 ! 1,3_ 11__l75,4!0,40!<0,05!traces ! o,oa !< 0,05 !traces!O,O100 ! 1,1 12 175,6l0,4~!~0l05!traces ! O,OOo. 0!`090 !traces!O,OllO ! 111 13 !75 !0.48!<0,05! 0,29 ! 0.07 !< O,OS ~trae~s!O,O100 ' 1~2__ 14__!75!5!0,45! O OS! 0,11_ ! Q,07 !<_O.OS !traces!O,O100_1 0,9 lS _1?4,8!0,47! 0,05! 0,07 ! o,oa !< 0,05 I.traces!O,OlOO !_ -?_ LO 16 !74,6!0,44! 0,05!traces ! 0,08 ! O,Co !tracPs!C10100 1 0,3 17~!74,8!0,44!<0,05!traces !0,01 à!O,05 à !traces!O,O100 ! 0,7 I _ ! ! ! !0.25 !0,20 ! I _!
la I74,2!0,4S!<O,S !traces ! 0,1 _1_0.07 Itr~ces!O,O100 ! _0,3 19 !75,2!0,48! 0,05! 0,04 ! 0 08 !< 0,01 !< 0,01!0 0100 !~ 0,2 ;1 25 _20 !7~.8!0,43!<0,05!traces ! 0,225! 0,10 !traces!O_,OllO ' 0 ~7 21 174,8!0,42!<0,05!traces ! 0,42 !__0.20 !traces!O,Ol?O_I. .?
_22 !59,7!0,57l_0,14l 0,036 ! 0,067! 0,0062! 0,02610~015G < 1 23 !59,7!0.55!0,0701 0,30 ~_0,060! D,0062!traces!0,0150 ! 7 4 !5S,5!0,5_1 0,14! 0~01~ !_O.OSO!< 0,01 ! 0!029!0,01/0 1 0,72 !59,8!0,54!_0~15! 0,023 1_0,060!< 0~01 Itraces!O, 0710 1 O, 26 26 _159,7l0,56!_0,16! 0,021 !_0,068!~ 0,01 ! 0~025!0,0190 1 _0,12 27 l60 !0,45!<0,09! 0,104 ! .0,03Q!< 0,01 1 0.0}0!0,01?0 0.2 !28,2!0,78!0,060! 0,0l1 !traces! 0,017 ! 0,040!0.C210 ! O.S
29 !24.610.75!0,03 ! 0,002 !traces! 0,79 ! 0.01 ! 0! 0130 ! <_ 1 - 35 ~ traces : < 0,001 O
- q~hi9 e~an7ple i9 equiYalent to a mean value of several te9t9; the oompo9ition~ of the granules ~aries in such manner that the sum of the mag~esium and man-ganese i~ between 0.2 and 0.3~p ~ .
... . . . ~ _ _ .

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T~e Rbove-de~orlbed ~om;~ress1on ~ests were carl1ed out on the ~ an~1e~ o~ Ex~i)les q, 6, lq, 19, 23, 2-~, 27 and 29 by meana o~ B
model TTD~ I~S~O~*machine a~ a ~?eed oi 5 ~m ~er minute a~d under an increaa1ng load of ~rom 0 to 10 tonnes. *TR~DE ~hK
GrRnules o~ a size o~ bet~een 10 and 15 mm were selected ror these test~.
Two p~rallel plane ~ur~nce~ of about 15 s~uare mm were produce~
by abra~lon to ensure the ~tablllty oi the granule betwe~n the two ?1ates Or the machlne~ The applled load wa~ at the top o~ the range .
The above teat gives the de~orm3tion value ~- e ie for thicknea~) agsln3t the applied load. Thi~ value enable~ to ~easure the load required to produce the ~irst crack and ~or crushing (di~integration) to be messured .
The reaults are glven ln the ~ollowlng Table:

Table Il Test Sludge ratlo % Load at which ~irst Dis1ntegration load crack a?pears l~ 7 0.5 0.5 l9 0.9 0~5 to 0.7 ; 5 ~4 0. 2 , 5 28 0.9 to 1 l.5 , 5 29 7.3 0~9 1.2 3~ 0.26 3 ~ 5 34 0.20 4 ' 5 It will be ~een Srom the ~bove that thi~ te~t i9 a ver~
rellable ~e~ns o~ determinlng the ~ludge ratio.
Example 31 Cooparative tests ~ere carried out in a b~th, the initlal composition Or which wa~ as follow~:

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_ 12`~ 3~
N i S O ~ 6 ~1,, 0 NlCl~ ~}l ~ ~0 ~1 F~So4 7~1~0 ; 11 g/l ~l3B~3 : l5 ~/1 Stnblll~er 20 ~/1 Brl~htener 1: ~5 cc~l ~rlghtnner 2: ~,5 cc/l Brlghtener 3: 18 cc/l ~ettlng ngent: 1 cc/l P~ = 3-5 Two 80 lltre tanks were ~illed ~ith the ~a~e initlal bath, one ha~ing ~our tltanlum bnskets (panodes) iilled wlth granules (tank A) and haYing an ~rea o~ 6.66 square dm, the other (tnnk ~) havlng thre~
baskets illled ~lth nlckel (area = 5 square dm) and anot~er ~llled ~lth lron (area = 1.66 squnre dm). These two tanki ~ere connected ln ~erles and a ~0 ~mp current ~ns pa~sed through the tanks, equlvnlent to ~3 ~ean anode dengity oi 3 nmp3 per square dm, wlth ldentlcal air ngltatlon in ~oth tanksd The test~ took 300 hours3 The tempernture ~ns about 60 C. The concentrntlon o~ the metnl9 in the t~o baths ~ns dellberately l~t to deYelop rreely.
The ~node yle~d in the case Or tnnk A ~a3 n~ost 100~, while in tsnk B lt ~a9 more than 100~ (about l03~ howing a che~ical dissolutlon o~ ~bout 400 g of lron on the 2360 g o~ iron dissolved.
The cathode yleld oi' the deposit in tnnk A was ~lightly better than that ln tank B, and wa~ about 94qo~
At tha end Or the te9t9, the mean compo9itlon o~ the coatlng ~as Yery close to that o~ the granule~ ln the case oi tank A (niekel ?3S, lron 27%) ~hile thnt Or the deposits obtained ln tank ~ ~ns C10Be tO 8~o nickel and 17~ iron.
The nickel plus lron concent~tion 1D t~nk B was Or the order o~

-87 ~ p~r Itri~ ~hlls lr~ tnnk ,~ l~ w~s ot t~ or~lt~r o~ tlO i p~!r L i ~ r~`
~ ult In coAtl~olllr~ tll L' l ~! V ~ 11 t l~SI It ~I r t` !l ~I Lt~ (ILIlltLorloi the b~lth ~Yhlc~ lt~d t~e ~l~ter~nces E~t th~' end ot the t.~t3) Ti~o nlckel concentrntlon ln an~ ~ wa~ ~bout ~;1 5 ~ r lltr~
at the en~ o~ t~le tes~s whll~ ln t~ A it wa~ nbout 75 g per liCre, The r~tlo o~ ~otnl lron to nickel plus iron ~er 2500 Ah ~3 8 + 0.~ ln tnnk A whlle in tank B lt was les~ than ~0~ ~nd about lOZ + ~.S~ ait~r 10 000 Ah ~nd up to the end of the tests, while in t~k ~ lt ~sn 38~ ~ter ?300 Ah, ~alling to about 20% with n~ctuAeiOns Or ~ 7.5~, The totD~ acld cona-~ption used to kee? the pll o~ the bath constsnt durlng the test perlod ~an subst~ntlally the name ln both t~nkB to ~ithln the ~easuring accuracy. ~ea~urement of the denslty o~ the two baths in tanks A and B showed ~ more rapid incresse in den~lty ln tnnk D (1206 ln the cnse Or ta~k A and 1212 ln the case o~ tsnk B a~ter 9 000 Ah, ~hile the den~lty oi the lnltlal bath ln J both tanks was 1170), thus coniirmlng the grea~r nlckel concentratlon lncrPsse in the case o~ tanX B.
Other comparatlve teat3 carrled out under condltlon~ similar to those described above showed that samplin~ Or the bath had to be more fre~uent in t nk B (sampllng of npproximntely 2 lltres or solutlon .~
out o~ 80 lltres o~ bath and replncement by nbout 2 litre~ oi ~ater) to ~eep the bath denalty con~tant:

T~nX~ wit~ separate anodes : about 4 to S sa~plings per 10 000 Ah.
Tanks ~ith granule anodes : 800Ut 2 to 3 ~amplings per 10 000 Ah.
Tha sbove examples ~ho~ the Qd~antage of using Franule~ to iacilitate operatlon o~ the bnth and give deposits oi the required composition.
These ex~mples also sho~ the dliiiculty oi determinlng the proper ~nodic sre~ ratio oi the nlckel bnsket~ and oi the iron baskets in t~e caae Or separEIte anodes. ;~ 34~
It Ahould be polDted Ollt that other studies have Ell~own th~t i t 19 pre~erable îor the oxygen, sulphur and copper contents not to exceed 0O03, 0.02 ~.cl 0,03% respectively.

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Claims (17)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process of electrodepositing on a substrate a layer of ferro-nickel matter, wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dendritic substructure and are of the composition by weight:
nickel, with or without cobalt impurity, 20 to 90%;
not more than 1% and not less than 0.1% in total of silicon manganese, magnesium, aluminum and calcium, the ranges for these elements being selected from the group consisting of:
silicon 0.02 to 0.5%
carbon 0.03 to 0.2%
magnesium 0.02 to 0.4%
manganese 0.01 to 0.1%
aluminum 0.01 to 0.1%;
and silicon 0.04 to 0.2%
carbon 0.03 to 0.1%
magnesium 0.02 to 0.1%
manganese 0.01 to 0.6%
aluminum 0.01 to 0.06%;
and silicon 0.04 to 0.1%
carbon 0.03 to 0.05%
manganese 0.02 to 0.08 manganese traces aluminum traces;
and not more than 0.2% of other impurities;
iron, the remainder of the composition.

2. A process according to claim 1, wherein the major particle dimension of the granules is between 1 and 15 mm.

3. A process according to claim 1, wherein said granules can withstand without disintegration a compression test which reduces the major diameter by at least one-third.

4. A process as claimed in claim 1, 2 or 3, wherein the granules withstand a compression of more than 2 tonnes with-out breaking.

5. A process according to claim 1, 2 or 3, wherein said granules withstand a compression of more than 5 tonnes without disintegration.

6. A process according to claim 1, 2 or 3, wherein in said granules the weight ratio of nickel plus cobalt to iron plus nickel plus cobalt is between 0.20 and 0.50 and the sum of said five elements is between 0.1 and 1%.

7. A process according to any of claims 1, 2 or 3, wherein in said granules the weight ratio of nickel plus cobalt to iron plus nickel plus cobalt is between 0.50 and 0.70 and the sum of said five elements is between 0.2 and 1%.

8. A process according to any of claims 1, 2 or 3, wherein in said granules the weight ratio of nickel plus cobalt to iron plus nickel plus cobalt is between 0.70 and 0.90 and the sum of said five elements is between 0.1 and 1%.

9. A process according to claim 1, 2 or 3, wherein the sum of the magnesium, manganese and aluminium in the granules is at least 0.05%.

10. A process of electrodepositing on a substrate a layer of ferro-nickel alloy, wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dendritic substructure and are of the composition by weight:
nickel, with or without cobalt impurity, 20 to 90%;
not more than 0.3% and not less than 0.2% in total of silicon, manganese, magnesium, aluminum and calcium, these five elements being within the ranges:
silicon 0.04 to 0.2%
carbon 0.03 to 0.1%
magnesium 0.02 to 0.1%
manganese 0.01 to 0.6%
aluminum 0.01 to 0.06%, and not more than 0.2% of other impurities;
iron, the remainder of the composition.

11. A process according to claim 1, 2 or 3, wherein the sum of said five elements in the granules is between 0.2 and 0.3%.

12. A process according to claim 1, 2 or 3, wherein the sum of the magnesium, manganese and aluminium contained in said granules is between 0.07 and 0.2%.

13. A process of electrodepositing on a substrate a layer of ferro-nickel alloy wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without u dentritic substructure and are of the composition by weight:
nickel, with or without cobalt impurity, 70 to 80%;
not more than 1% and not less than 0.1% in total of silicon, manganese magnesium, aluminum and calcium, these five elements being within the ranges:
silicon 0.04 to 0. 1%
carbon 0.03 to 0 05%
magnesium 0.02 to 0.08%
manganese traces aluminum traces and not more than 0.2% of other impurities;
iron, the remainder of the composition.

14. A process of electrodepositing on a substrate a layer of ferro-nickel alloy, wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dentritic substructure and are of the composition by weight:
nickel, with or without cobalt impurity, 50 to 70%;
not more than 1% and not less than 0.]% in total of silicon, manganese, magnesium, aluminum and calcium these five elements being within the ranges:
silicon 0.1 to 0.2%
carbon 0.03 to 0.1%
magnesium 0.03 to 0 08 manganese 0.01 to 0.08%
aluminum 0.02 to 0.06%, and not more than 0.2% of other impurities;
iron, the remainder of the composition.

15. A process according to claim 1, 2 or 3, wherein the chloride ion content in the electrodeposition bath is between 10 and 40 grams per litre.

16. A process according to claim 1, 2 or 3, wherein the ratio between sulphate ion and chloride ion concentrations in the electrodeposition bath is between 1:25 and 1:4.

17. A process of electrodepositing on a substrate a layer of ferro-nickel alloy, wherein there is used as a soluble anode an anodic basket which is filled with granules of ferro-nickel which have a structure which is basaltic or is equi-axed without a dendritic substructure and are of the composition by weight:
nickel, with or without cobalt impurity, 20 to 90%;
not more than 1% and not less than 0.1% in total of silicon, manganese, aluminum and calcium, these five elements being within the ranges silicon 0.02 to 0.5%
carbon 0.03 to 0.2%
magnesium 0.02 to 0.4%
manganese 0.01 to 0.1%
aluminum 0.01 to 0.1%, and not more than 0.2% of other impurities;
iron, the remainder of the composition.