No abstract

An investigation into the general and pitting corrosion rates of rolled homogeneous armour (RHA) steel in immersion and salt-fog environments is presented. Although the mechanical properties of RHA steel have been studied, the corrosion effects on RHA steel have not been quantified. An immersion environment of 3.5% NaCl was used to induce corrosion for four immersion samples. A Q-fog corrosion tester was used to simulate a salt-fog/humidity/drying environment for four saltfog samples. The different mechanisms of corrosion and their rates were quantified through mass loss, laser profilometry and scanning electron microscopy. The immersion samples show a linear rate of corrosion of 1.47 g/year (R 2 = 0.994) throughout the entire testing period. The salt-fog samples had a significant mass gain for the first 500 h of corrosion, as the corrosion products are retained. Immersion samples showed no signs of pitting, while the salt-fog samples had sustained pit nucleation, growth, and coalescence.

It ~vould be proper9 I think, first. to esplnin why t h pint and riiriiish industry is representcd nt. this niccthg. I n sonic nicnsure tlic plastics nnd p i n t iiiid vornisli indust.ries covcr siniilar ground in tlint t.licy lrotli iitilize rcsins-nntural nnd synt~Iictic--nnd pigments. Tlic rduc of t.hc pniiit nnd rnriiisli tmde is fully t,\venty million pounds sterling. It rcprcscnts considerable eiiiployincnt not only in mnnufncturc hut rilso in nppliciitioii. !rlie fibwres for the 1930 Board of Trndc census (pu~)tishcd in 1932) shoived t,hc value of goods niadc nnd work done (gross output) to be flS,m,000 and the cost of niiiteriuls eniployetl in the inc1ust.r.y ivns tlicn 20,616.Analysis of tlicsc figures .untlcr major production clnesrs showed : piiiiits and I)igiiient.s-itI,Irros. 5,500,000 cwt. of viilue i l ] i J l~O X . 113,000,000 ; viirnislies, inclritling cellulose types-nppros. 9,@00,00~ gal. of viilue ~~tppros. 13,750,000.The voluine of overseas tr:itlc iis nssesscd n t tlint time nas considerable as is slioivn by figures of l,418,0IlO cut. for csport rind 1,896,000 cwt. for retained iniliorts of paints nnd pignients ; nnd 1,290,~OO gnl. for esport itntl 132,000 p l . retnincd iniports of ritrnish products. Tlicsc figures demonstmtc tlie dominnnt posit,ion of 13ritish-iniidc varnish products in the honic innrkct and of t.lw extent to wliich t,hey arc apprccintcd nl)ronil. Since 1930 t.lic industry will h a w shown cspnnsion in nlniost ewry section.The iiioney vnluc of csports of paints, eiiiiniels, varnishes, and liicqucrs for 1934 rind 1935 Iias 1)wn est.imntccl n t 53,000,000 per aiinuiii approsinintcly.Used to IJC? flOIal!%k,OOO. The il\'Cra@ I l I l I l 1~) C~ of IJCrSOIlS PIGMENTSAs to the rnw niateriitls used, white lead in linscctl oil is still tlic yard-stick of tlic industry, unti, inclcetl, t h r c is sornct~liing unique itbout tliiit conibinat,ioa of ~iignicnt nntl vehicle wliicli has not been np~~ronchcd by ot.hcrs, certainly not in such a simple form. For onc rcnson or another the Urit,isli consumption of \vhitc lend is not quite as much as it \vns thirty yairs cigo, n t which tiinc! it nniountctl to nliout 50,000 tons a yciir, nltliougli in t,hc interim period the quiint.ity consunled liiis rcnclictl iiiucli lower lcvcls tfinn tlie present.Of t.11~ other wliitc pipicnts, zinc osidc antl lithopone urc nest in order of irnportnnce. Tlic world production of lit,hoponc ivns 360,000 tons in 1929. Since t,Iiiit. tiine production has undou1)tcdly incrcnsetl consitlcrnl~ly, iind todny English production is c n p l h of taking cnre of honic consuniption wliicli ~voulrl appear to I)c ubout 50,000 tons per nniiuiii, of wliich approsinintely 34,000 tons goes to tlic p i n t trndc. The totnl consumption of the \\-hito zinc pigments by tlic p i n t industry must be consitlcruble, but zinc osidc is rcnlly niorc economicidly iiiiportuut to rublier t h n it is to paint.Tliird in tlic wliitc pigment list riink titanium diositlc pigments with a totnl world consuniption in all forms of t.he order of 80,...

No abstract

iiccotiiptuiyiug ligurc the three types iire illustriitctl l)y ciirvcs yicldcd by copper, zinc, i i i i d iron ri!spcctivcly ; itiid iti citclt.c:tso :i ~ilicitoiuicrogrii~~li of t Iic corr~~s~iontliiig rcnction prndiict is given for coml)itrison. Tlic firtit ciirvc--~ qtiiiclriitic pit riilJolit-rcl)rcseitts tlic turnishin,n of coppcr in nil ortliniiry irttloor :itniosplicrc. lZerc tlic reaction procliict, frotti tlio eiirlicst stages, tnkcs t,lic forin of II contittuoits citvclopc, t81irougli nliicli tlic nttncking iitniosplic:re is iiblc to tlilfusc a t it rate that is iiivcrscly proiwrtioiiiil t o tlic tliickticss of the film n t iiny given tinic. Siiicc tlic primtiry filtii is in opt.ionl contiict with tlict iii~!titI, its riitc of thickciting itiity IIC followed by ol)scrviitg tlicl cltiiriictcristic S C~~I C I I C C of i~itcrferc~ico colours to wliicli the process gircs rise. l'lint the process is coiitrollctl cnt.ircly by tltc propertics of the itii~iiilIy-foritic(I f i l i n is sltowi by tlic fiict t l i i t t whcn oiice tlic tiictiil sttrfiicc is covered, tlic composition of tho i i t~i t~~p l i c r~ tiiiiy vary \vitltin wide liinits without ~~rodiiciiig iiuy cltringc iti tltc 1)rogress of tlic tittrick ; the quiidriitic piiritlwlii is uiitlcflrctcd from its coursc.A sul)-division of tlio lirst group is ttcccssriry t o includc tlic case of ti tiictnl sucli its iiluniiiiioni, in which the siirfiicc t~ccouics quickly covcrcd with it tihi wliich, under f i i~o~r i~l~l c conditions, in pritcticnlly iiitpcrvious to furt,licr advnncc of t,lic ntmosplierc ; tlic cliiirrtctcristio curve (slioivn in I)rokcn litics iii tlic fgiirc) tlius bcco~nes ptirtillcl to tlic t h e nsis. It is ivcll ktiowii tlt~it tho resisttilit, qtiiilit.icu of ciluinitii~im iirc tluc cntircly to the pro1)crtics of thc osidc film with which it is normnlly covcrcd ; if tlic cottditioiis nrc so clioscn t h t tltc oxide film ciinnot IIC muiiitiiinctl (ns obtnitis for csimplc.wltcn the s i i r f i i~o is ttniiilgnnintcd) tltcn corrosion 1)rocccds at :t riipicl pnco cliriritctcriRtic of tho intrinsic rctictivity of t,hc mctiil. 21 thC JXIrt Of thC I l l C t i l~ to " gCt lJllCk 10 lllItl1N!." ollly