DE1521173A1 - Chrome plating process - Google Patents

Description

Patent attorney

Frankfurt / Main-1
ParkstroBe 13

4909

Bethlehem Steel Corporation, Bethlehea, Pennsylvania, USA Chrome plating process Zusati sub patent ... », ... (patent application 8

The invention relates to the production of chromium-containing apply to strip steel and in particular to overcUgen made of a chromium ·· iron alloy »

The object of the invention is sugrunde, on the surface of steel areas, g.B. Strips, sheets, plates, rods, Bars and wires, a firmly adhering bullet-shaped base a C & roa-Eiaen legitimacy to bring up the Chromium alloy is said to be through diffusion of a SohutiatBoaphäre be made. The effect of the school atmosphere »oll are reinforced by controlled amounts of chlorine gas «»

In the case of the production of oversupply from a uron alloy Strip steel or similar steel objects duroh compacting a chromium-containing powder on the stone surface and subsequent sintering to produce a diffusion between the powder and the metal pile should be the

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BATH ORIGINAL

Sinterprosefi vorsugswelae in the finer ataosphere from nahesu 100% hydrogen can be carried out. £ β is «was * 8glioh To maintain such an atmosphere under ideal operating conditions, the atmosphere will if large amounts of property are to be chroused, for example 90 ob wide (36 inch) steel strips bit with a wlokelength of 4 fins or more, often contradicted by substances influencing the interproseB in a harmful way "

The impurities can be fiery caused by leoice or aua Stoffen a "Boden de" Ofene in the Sinterateoephäre elnee Sintering or annealing furnace get · Beia Yerchroaen from large Pieces can therefore always be eaten, enough Vaeeeretoff ■ Make the required leg length. The figured out VeruMreiniguagem in the Sintere ttso ^ sphere and Saueratoff, Carbon and nitrogen, "those there" Cbroapulrer or ohroM-containing powder, which before sintering on the metal * underlay is compressed «a high affinity beeltat.

The »» all-often occurring in the Sl «terat» oephllre occurring Yeruareinlgui ^ ist natllrllsh Smuerctoff «Saueretoff at a Simterprosee, at the av & Bsratellung dee überauga % in IhAtWQT Vtommfetit wijri _f %« ale the & D ^ da rsfes d * o Cbroffiss Xm. im !! »« a ä * s? Stafilunttrlag · and dee Blaeas In dms vtirdioltemd ^ Ήν? Τ ** «^ .thalteade powder

The stdzke & ttiiü§ £% <& m Wssms mm Mmmtoft | Bhrt 1 * a "sintering furnace, ier a · g £ ® $" Stadroll · au · "tahlbe · * contains, both of which rarely" it "Ines * er <3 £ ehtend * n »Ctaron containing silver would be shown, as a result of a reaction, the oxygen and the» ear »seibat small amounts of oxygen in the ataosphere of the furnace

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react almost completely old to the compacting chromium. During the reaction, the oxygen forms on the free chromium surfaces an Oxydflla, eo that the reacted chroa particles to be prevented, in the Elsen dee steel belt. In a similar catfish the reaction of the Elsene of the steel pad old of the compacting powder narrowed, Wer.3 Finally, a mixture of chro «and egg powder or a powder of a Chroa-Eieen alloy sur When the soleplate is used, oxidation of the Chroas 1 «powder prevents rapid diffusion of the chromium and iron cells of the compacting material self.

The formation of an oxide film on the chroot above the compacting Layer caused by impurities in the interatosphere can progress as far as that within sensible sinter seldom no susaaaechangende hatsohioht is formed from a chromium alloy, even if the sintering temperature is kept at a much higher value than normal required for chroa-iron diffusion "

In the production of transfers from chroal regulations Steel strip by compacting a chromium-containing powder on the strip and then sintering the object can by dl * .controlled introduction of chlorine gas in the annealing furnace during "* the sintering process UbersUge with the quality of stainless steel and old more uniform Bead to be obtained. Sos chlorine gas can be independent or like ae with the hydrogen gas introduced into the furnace become, the euid maintaining a reducing ataosphere during heating, sittering or warming up urd Aljfcühlesa is used-

Ia? Ol £ don is sauteed, on "wwhe tfsise the chlorine gas

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BATH ORIGINAL

in the case of the formation of βIn β over a chromium alloy on a linear or strip-shaped steel base, it can be used as an accelerator. A roll of tape weighing 4,435 kg (9,790 pfttad) aua 1.3 aa (Gage 18) stronga steel bleoh old low "carbon content (0.009 + tohleaatoff)," is overturned with a liquid consisting of low-alcohol alcohol, and daa The old band provided with a film is passed through an Ilieflbad a · powder made of an Ohroa * ISiaen alloy «Sae powder used let ala eiaplex-ferrochroB confesses and consists of 71.3 Jt Qhroa, 0.35 * manganese, 1.42 * 8111olua, 0.01 tons of carbon "ad Beet Sieen. The powder has a particle size of 0.07 $ aa (200 aeah US Standard Slevee Serlee). The band barks when it exits the Plioflbad on both inch) · The tape is then fed through a whale mill, whose catfish have a diameter of 710 aa (28 inches), whereby the powder is compacted onto the tape. At the Welswerk, the powder is transformed into a porous, semi-adhesive metal cap, in which the powder particles that are directly adjacent to the tape are pressed against the tape to create a firm mechanical bond.

Because of the porosity of the compacting powders, Saueratoff or oxide impurities In the surrounding atmosphere, the free surface of the powder reacts and forms a chrome oxide film on the surface.

Bach the compaction is the role with the help of a 0.6 aa (0.024 inch) thick, sldksack-veneered spacer wire

909845/0331 bathroom original

Wrapped openly, about 50 sa (2 inches) below the top tape the tape roll lies

The roll of tape is now ready for the sintering process upright on the pillow block or the base plate of the annealing furnace posed after Lee-Wilson. In such an oven there is an inner jacket over the base plate and the roll of tape aua stainless steel «The coat that conceals the ataoaphaira. that surrounds the Bolle to be treated has a volume of about 16.57 cubic meters (585 lubikfufl). Gas pipes run for the introduction of hydrogen and Ohlorgaa through the base plate, which carries the roll of tape · The inner jacket is old of a liquid on the base plate Metal (woode-raw metal) tightly fastened · Bin · aua steel Existing furnace wall lined with refractory material surrounds the inner jacket and completes the furnace »gas containers Radiation pipes in the furnace wall guide the lur Maintaining the temperature inside the batch) outputs, required heat. The temperature will sit fheraoeleoenten sat in the base plate, which protrude into the Bolle.

The atmosphere la inner cladding is cleaned old dry "9a · 4 J * hydrogen and 96 $ nitrogen, daa old at a rate of 25.5 a * / 8TD (900 Kubikfufl per hour) auatrOat, the oxygen concentration less than 1 bia i" and the dew point of the oasis flowing out has dropped to -40 ° C (-40 ° F). The Oaβzufuhr is then switched off and ea is almost 100 jtlger old hydrogen at a rate of 25.5 s ³ / 8td (900 lubikfui per hour). After the hydrogen concentration has reached 75 + , the furnace is placed on the base plate and the heating process begins ·

909845/0 331 ■ original bathroom

At the beginning of the Brwarttu & gaproeeeaas there will be »periodic meaeungen dee dew points in de? Within Behendlungsatiioephäre dee inner shell vorgenoaaeit Jfech · 2 1/2 hours, the Ausgangataupunkt -29 ⁰ C ( "20 ° 7) has reached and then ainkt etetig at 427 ⁰ O (800 ° F) to -43 ⁰ C (-45 ° I ) away. This temperature is then raised aaaaaaaaen old hydrogen, Ghlorgaa la the Sinterataoephere. The flow rate of the chlorine lake * is 0.25 ar / dtd (9 cubic feet per hour) »Ib inner coat is maintained for a long time atnoaphärieoher bridge and therefore the stepping Oaβ loads the work area that surrounds the binding roll to be treated, old an oeach speed, dl Aaheiu equal to the dea listed hydrogen and chlorine gas let,

When the atmosphere in the inner dumbbell has reached a temperature of 927 ° 0 (1,700 ° F), the temperature is maintained for about 24 hours dea Sieen of the Bandetahlunterlage Biffuionen take place. AuBerdea find Dlffuelonen "Vlachs the chromium la powder and any therein containing Sieen- or Mick Elan parts etatt · During ereten 12 hours dea Durchwär" ungepro "eeeee _t after which the Gblorauatroa is interrupted warden ait the velocities above continually chlorine and hydrogen in the Treatment initiated. The hydrogen etroa remains continuously switched on even during the second half of the warmth-through period and also during the main part of the connected coolant proaaea · after 24 hours warming-up, the · healing of the furnace · is switched off and the ganae oils can cool down »Xaoh the tape roll has about 3 hours cooled to about 704 ° C (1,300 ° f), and at this temperature the protective cover is

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BATH ORIGINAL

Eraetst furnace and removed by a cooling jacket "When calibrating the tape roll after about a further 1/2 β 8tunden to about 80 ⁰ O has cooled (175 ° I), then the hydrogen" ufuhr is interrupted. For this purpose, a gas containing 4 * mass and 96 * Btlokatoff with an Oeeohwlndlgkelt of 25.4 aValn (900 Kublkfuö per minute) is introduced. The cover of the batch is removed after a further cooling of the roll of tape to about 57 ° 0 (195 * I).

All results of the honorable treatment are given to one chrome Schutsschioht by duroheohnlttlloh 0.05 aa (0.002 inch) thickness, dia ahm "8ohade" an unauohen In boiling, 20 Vbluenproientige nitric acid attahert · This means that the Bchutteohicht on a « Steel belt, the same furnace and the conditions are perfect, However, in Abweeenhelt of OhIor, also old elnea condensed Powder fce traded did · do such a thing Let the sintered beechwood be treated spotty and there are large areas without 8ohutsaohloht and areas where the Sohutaechlcht port * · let '·

It is assumed that this is due to the communication of Ghlorgas In the tfaaeeretoffataoaphäre the oxides on the surface the powder particles are reduced before the start of diffusion and also oxidation during the warmth and interproseesee be prevented·

In another implementation, a weight of 2,265 kg (5,000 pounds) heavy tape roll old 952 * 5 M (57.1 / 2 nominal) Width also 0.95 on strong steel strip (Oage 20) like the previous one Example old elnea alcohol purple and with coated a Siaplex Ferrochroa powder “Sine others 2,265 kg (5,000 pounds) roll of same tape

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BATH

Oröß · and Art wit the first «roll of tape is in a similar catfish» provided with an alcohol layer and old a normal Ferroohroa powder old low carbon content (0.08 J * carbon, 70.9 * Chroa, 0.43 Jt Slllolua and 0 , 05% manganese) coated "bie two band rolls of a 4530 kg (10 000 pounds) are combined heavy Bolle then su, the bit a is wound open to strong Abst & ndsdraht (0.024 inch) 0.6. This roll of tape is placed on the base plate of an annealing furnace and the old inner jacket is covered o The jacket is closed and the furnace is put on. Before heating, the atmosphere of the inner mantle is purified with a gas consisting of 4% hydrogen and 96% nitrogen. During the heating period, the dew point of the exiting gas is sat every hour until a temperature of 427 ° C (800 ° F) is reached. To maintain a dry ataosphere, the roll of tape is held at a temperature of 427 ° C (600 ° F) for 5 hours. Thereafter, chlorine gas is introduced into the atmosphere at a rate of 0.13 Vh (4.5 cubic feet per hour), which corresponds to 0.5 J * of the total volume of the interior atmosphere. The temperature of the roll of tape is gradually increased to 927 ° C (1,700 ° F) while the flow rate of the chlorine gas into the sintering atmosphere is maintained at 0.13 nVh (4.5 cubic feet per hour). During the entire warming process, the hydrogen is introduced into the ataosphere of the furnace at a rate of 25.5 aVh (900 cubic feet per hour) The flow of hydrogen is maintained. Halfway through the sintering process, after 12 hours at 927 ° C (1,700 ° F), the flow of chlorine is switched off. As in the previous example, after 24 hours

909845/0331

Through heating, the heat supply to the furnace is interrupted and the Batch cooled down »The hydrogen flow is maintained, until the batch has a temperature of about 143 ° C (290 ° 7) has reached, and at this temperature is then during the rest of the ibkUhlseit a 4 * hydrogen and 96 * sticket off containing Oae introduced instead of Waeseratoff »

Both sections ¹ of 2,265 kg (5,000 pounds) each of the most commonly used roll of tape contain a satisfactorily chrome-plated steel strip that is resistant to cohesive 20 pounds of nitric acid.

The most effective results are obtained according to the invention Chlorgaa when the ateosphere exercising the tape role is essentially free of moisture before the sintering temperature is reached because water vapor in the atmosphere increases the likelihood of chromium particles being oxidized. As the examples «own, the dew point of the atmosphere before / sintering should preferably be around -40 ° C (-40 ° F).

When introducing chlorine into the treatment atmosphere, higher proportions of water vapor, nitrogen, carbon dioxide and oxygen can also be let in »during the warming process there are often up to considerable amounts of impurities in the atmosphere, so that they are more harmful Chromium and iron compounds can form the one prevent later diffusion. During the warming aproBeaaea and the initial stages of the sintering process are chlorine gas extremely effective as it uses during these heating processes the oxide film or with films of other compounds reacts on the compacted metal particles, so that elementary Chromium can diffuse quickly for the tape "

In both examples, n d is the chlorine even in a

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BATH

Fraction of 1 i * and once introduced in an amount of 0.5 1 · in besug the Wasserstoffatooaphäre »£ a, smaller amounts of chlorine can, down tu O ₁ I used i" "because the amount of chlorine used naturally existing from the crowd Impurities depends

The upper limit of chlorine depends on two vectors. Bratens is in the "Bureau of Mines Bulletin Vr. 503" under "Limits of Flammability of Oases and Vapors", page 23 »admitted that chlorine and hydrogen become explosive in a known manner if the chlorine content is above 11 56 *

Secondly, it has been found that an excess of chlorine can cause erosion effects Large quantities of chlorine in the body seem to result in physical disturbances on parts of the openly wound reel of tape, so that as a result an uneven distribution of the unauthorized layers is obtained. Although this ineluctance the layer neither the appearance of the surface nor the resistance of the layer to boiling nitric acid local areas can be influenced by a static test form, in which the layer is very thin, Dürpie spots of the layer would be the degree of formation or the surface treatment grass »to which such a coated article could be exposed, since the thin areas are lighter than the rest of the rubble will be split or torn »

In order to avoid erosion of the layer, the sugaführte during Slnterns amount of chlorine is "limited to a content of 0.5 percent by volume of the total sintering atmosphere during the ErwärmungsproBesses before sintering, the chlorine can be up tu a proportion of 1 i> of the total volume of the BehandlungatmospUäre or If necessary, a slightly higher proportion can also be initiated.

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BATH ORIGINAL

Since chlorine is very poisonous, they practice induction the use of chlorine UbIlohen Voraiohteaaflnahmta observed so that the outflow of chlorine la die Bauet, la them when the operating staff is located, it is avoided «

Dbβ introduction of chlorine gas into the atmosphere should be carried out before dta Cooling of the batch can be interrupted * Thee can bath approx of the Interproteaaes or, preferably, some other place during the sintering process, for example after halfway through On the other hand, o The chlorine should be taken from the batch Evacuate the surrounding atmosphere before cooling off begins to prevent the formation of chlorine compounds condense and adversely affect the surface of the layer.

When exercising the trfinduagsgtmäfiea procedure can Metal powder can be applied to the metal backing, the chrome, an Eiaen-Chrom-Iegleruag, a mieohung of Iron and chrome, an iron-chrome alloy with liokel, a Mixture of chrome and liokel, an Eiaen-Chrom-Ilckel-Le- ' alloy and a smell of iron, chromium and oil powder included "If alloy powder is used, iron, chromium or Hickel can be added if necessary" Any combinations or are also suitable Mixtures of these powders, as long as the composition contains enough chromium that a Chron-Eieen composition in the Schutachicht can arise «To produce a red-free alloy layer the chromium content in the powder should be mineatena 20 percent by weight is »Small proportions of inert material or Subataneen, which do not affect the manufacturing process in a harmful way, can also To be at the fore

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BATHROOM OBlGiNAL

A truly continuous, non-porous and stainless Schutseohicht resists boiling 20 volumenprosentlger nitric acid (based on 100 i "HMO) ₀ received order a Korroslonswlderstand dieeer size su" mufl the Bohutssohicht relatively nonporous be <>

If not the carbon content of the tape and the applied Powder is below a certain, preselected maximum value, then the Eusamnengeeetate Oegenatand is presented decarburizes the sintering process o The effective carbon content of the tape should not be more than 0.01 during sintering Oewiohtsprosent be · On the other hand, the carbon content should of the applied powder so that the desired effect is achieved arises, do not lie above 0.25 Oewlohtaproaenten "

The term "effective carbon content" is reviewed on that carbon content in the metal base or the 8ohutsaohioht, the sur formation of harmful Ghroacarblde sur is available. These carbides make the protective layer brittle and thus limit its deformability dea with the SchutsUbersug provided product · In addition Sohut coverings with carbides fill a smaller amount Korroelonswideretand ala soleplates free of carbides »

If the coated tape has the strength properties of carbon steel should be given, then a Tape with a carbon content of more than 0.01 J (used if there is a complexing agent such as "titanium" in the tape is included. If titanium is sugegen in sufficient quantity, eo that it reacts with almost all the carbon in the band can then be the diffusion of carbon dee ribbon

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into the Sohutaschlcht during sintering · and the formation unwanted chroacarbides avoided in the Schutssohloht " Other garbinds which can be used from binding the carbon are chromium and hob «if la bend eyeballs on the other hand, the carbon in dl · ·· »white ·· m bind, then care must be taken that the effective carbon content of the tape is in solution Carbon, the free old dea chro »la twisted powder can react to a value below 0.01 Jt.

The total effective carbon content ia metal strip and Id metal powder should be sufficient during the interprocess be low, so that the resulting alloy hole Resists boiling nitric acid even in this case O

Analysis has shown that the layer produced made entirely of an Eieen-Chroa alloy, or if so Nickel is used as outputs »terla1, from an iron-chron-Hiekel alloy consists, the alloy is created by a metal diffusion swlsohen metal to metal Iron and chrome, or "wipe iron, chrome and hickel." To the Hiring the correct £ iffuaionagradea, the. an alloy * layer of kouoersiellem vert must, should · dl · Τββκ temperature during the sintering process. swisohen about 843 ° 0 (1,550 ° F) and 1,830 ° C (1,900 ° »). at a temperature of 843 ° 0 (1 550 ° f) a · minimum time of 12 hours should be maintained, although depending on the Lack of the desired alloy, doho the Chroeneng · in the alloy on the surface of the layer, sometimes much longer times are sweckmKBig ο BIa is sintered limited upwards solely by practical considerations,

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Bel Jeaperatures over 843 ° 0 (1 550 ° f) nlMrt dl · required * Loaned Mlndestaelt In Inverstr Wels from *

With Proper Use Of Chlorine In The 31nteratao · In addition, the chlorine does not only act as an accelerator for enlargement * •• tion of the diffusion velocity, even if in the Interatttosphere Contamination In The Form Of Oxygen or oxides are present, but in the presence of d ·· B · * » Accelerators can also be used as a discount. be sugelasten calloused powder »

Another advantage, which is due to the use of chlorine, is the greatly increased ductility of the coated products. According to the method according to the invention, an object coated with an alloy came in cross-section, among other things, about 80% glue The effect of chlorine is of utmost importance in the manufacture of thin, thin objects, since the strength of the Bajad steel "during sintering" is limited to a value at which the rolling oil of the sintered container is too low «InetUrit. Ultatr value is not recommended for a minimum "strengthening transmission" of "twai ö _t 4i en (0.18 inoh).

'tfaoh the present in Seäuhrelbung ** i? d the rest of the free sole layer because of the isflniSusie Ümsuh a diffusion of chrome into the steel base tm & ton bit · »on · the · steel base« rlag · in the compacted pul> er while ä% ® sintered bar ·· ·· manufactured.

/ The term "strip steel * ¹ also includes sheet steel and steel plates. * The proportions given are all oily sprouts, except when it is chlorine." The proportions of chlorine are given in percentages by volume.

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Claims (1)

Patent application Process eur production of an element according to patent application θ dee main patent 84, characterized in that a metal powder containing no less than 20 + ohrob and no more than 0.25 pounds of carbon is applied to the surface of the band, that the powder is applied to the The band is compacted, since the band and the compacted powder are sintered in a Sohutsatnoephäre containing not less than 0.1 yoluene per cent of chlorine for one side and at a temperature which is sufficient, inter alia, to cause diffusion between the band and the powder, and form an alloy layer adhering to the moisture on the surface of the band, and that the effective carbon content of the band during the internal process does not exceed 0.01% by weight. 909845/0331 BAD ORIG'-NAL