Ei^ϋ §J± fi_a_a.JiSJl__J_._l_l of. jnv._|_liio_l T is invention relates to compositions and methods of us i ng the compos itions in prepar i ng ferrous meta l components for subsequent surf ace el ectrop l ati ng by preparing a dispersion containing an acid and a sequeste¬ ring agent, immersing the components and abrading media i n t e d i spersion, and ag itati ng the components and the abrading media whi le maintaining the components and the media immersed in the dispersion. Simi l ar technology has been known heretofore from such d iscl osures as Hays Un ited States Patent 2,890,944; a ser ies of Un ited States Patents to Herman Ben Snyder including 2,940,838; 2,981,610; 3,052,582; and 3,061 ,494; and ichaud et al United States Patent 4,491,500.

In accordance w ith the improvements of the present invention, the compositions used are l iquid dispersions. I n l iqu id form, the composition has, by eight percent exc l ud i ng any water content; up to about 2C > oxa l ic ac id; up to about 50 of phosphorus sequester i ng and buffering agents; the ratio by weight of oxal ic acid to phosphorus agents being in a range of from about 0.70:1 to 0.20:1 and pref erab l y such as to prov i de a co pos i- tion pH i n a range of f rom about 3.5 to about 7; an amon i fy i ng agent; a surfactant; and a suspend i ng agent suff icient and effective for enab l ing the suspension of the constituents in water so as to form the compositi n.

It has been known heretofore in the manufacture of ferrous metal components that electroplating of such components may serve the dual functions of protecting the ferrous material against rust or other deterioration and enhancing appearance. For such reasons, it is com¬ monly done to plate hand tools such as wrenches and the l ike with bright electroplate f inishes. In preparing components for such .f inishing, It fs important that the surfaces to be p l ated have a certa i n degree of smoothness for appearance sake, and sometimes Important that hey be pol ished. hi le such pol ishing has been done in a number of different ways, chemical processes for metal removal have achieved some success and accep¬ tance, and have fol lowed general ly the teachings of the prior patents l isted above.

In processes of the type described, there is a constant balancing of harshness against producti ity. In attempts to achieve high productivity of components and short cycle times for the use of equipment, some users have attempted the use of strongly acidic solu¬ tions. In attempts to achieve desirab le surface f ini¬ shes, other users have attempted the use of less acidic dispersions. In both instances, problems may be encoun¬ tered with exhaustion of dispersions used and eff luents created. Attempts at prolonging the usefulness of solu¬ tions have Involved the use of sequestering agents to assist in avoiding exhaustion.

finlsi __ __,__S__,_L__,±i__, n. of. J.Jlv.en.±_Lon. Havi ng i n mi nd the efforts made i n the past and the prob lems encountered, it is an object of this inven¬ tion to achieve chemical ly pol ished surfaces in an opti- al processi ng time and w ith m i ni mal undesirab l e ef¬ f l uent. I n real izing th is object of the invention, a process of the genera l type br i ef ly descr ibed herei n- above is improved by the use of an organic acid disper¬ s ion wh ich ach ieves control l ed meta l remova l at a de- sirab le, pred ictab l e, rate. Production capab i l ities using the dispersion contemplated by this invention are better than those accompl ished using the harsher solu¬ tions previously used, whi le the eff luent from the pro¬ cess more nearly approaches a chemical ly neutral waste. Yet another object of this invention is to ^" provide co os itions h ich may be formu l ated and hand l ed as l iquid dispersions, and further dispersed into water to provide the necessary working dispersion as needed. In real izing this object of the present invention, appl ica- tion of the dispersion to a f low-through type of process is faci l itated and simpl if ied handl ing is accompl ished for certa i n users wh i l e reproduc ib i l i ty of resu l t i s achieved.

_L__._-._-_LJ___._- Des,c £J_p_tj_ojτ. of. in____Il±io_l Some of the objects of the invention having been stated, other objects w i l l appear as the description proceeds. Whi le the present invention wi l l be described more fu l ly herei nafter, it is to be understood at the

outset of the description which follows that persons of skil l in the appropriate arts may modify the invention here described whi le sti l l achieving the favorable re¬ sults of this invention. Accordingly, the description which fol lows is to be understood as being a broad, teaching disclosure directed to persons of skil l in the appro riate arts, and not as I i lting upon the present invention.

Stated general ly, the compositions contemplated by the present invention are l iquid dispersions adapted to be nixed w ith ater and used in a et process abrasive finishing apparatus for ferrous m tals, such as a tum¬ bl ing barrel or the l ike. The l iquid dispersion com¬ prises, by weight percent, up to about 90 ater. Ex- eluding the water content, the dispersion comprises up to about 20 oxal ic acid; up to about 50 of phosphorus sequestering and buffering agents; the ratio by weight of oxal ic acid to phosphorus agents being in a range of from about 0.70:1 to 0.20:1 and preferab ly such as to provide a composition pH in a range of from about 3.5 to about 7; an amonifylng agent; a s rfactant; and a sus¬ pending agent sufficient and effective for enabl ing the suspension of the constituents in the ater present so as to form the composition. The phosphorus sequester! rg agent may be any of the inorganic phosphates which display the characteris¬ tic of sequestering ferrous rnetal Ions, and/or many of the organic phosphates which display such characteris-

tics. Those which have been found to perform wel l in the compositions of this invention are pyrophosphates, tripolyphosphates, and phosphonates. That which is most preferred for certain compositions is tetrosodium pyro- phosphate. The phosphates used may, in fact be produced by chemical reactions occurring as the composition is prepared, as entioned hereinafter.

The buffering and/or ammonifying agent(s) may be any a monia releasing or generating material which wi l l have the effect of moderating the pH of the dispersion. It has been deter ined that the comb ined effect of the acid constituent in removing metal and the sequestering agent in holding metal ions in dispersion and .preventi ng their re-deposition onto the components in a plating type process is pH dependent, and i l l not start and/or proceed properly at pH level s bel ow about 3.5. Thus it is important, in the compositions and methods contemplated by this invention, to control that factor. In the l iquid dispersion using such aterial s, such control may be accompi ished by a balancing of monoammo- riium phosphate and c! i ammonium phosphate. In certain preferred forms of the invention, the eight percentages of these constituents Is equal. In other operable forms, the balance may shift more to ard one or the other of the two, with increasing quantities of dia mo- nium phosphate favoring higher pH and increasing quanti¬ ties of monoammonium phosphate favoring lower pH for the dispersion and the operating dispersions. Alternatively,

the ammonifying agent may be derived from such materials as l iquid ammonium hydroxide or gaseous a monia, ith reactions occurring on preparation of the compositions of this Invention leadi g to the appearance in the composition of the phosphate forms. In the latter in¬ stance, pH control wi l l often be faci l itated.

In order to assure that the compositions of this invention more easi ly enter dispersion with water which mixed for use, it is desirable to incorporate a wetting agent in the form of a surfactant. A preferred surfac¬ tant is a non-foa ing, non ionic material, and It is further preferred that such ateriel be of a lo HLB type.

The ratio of oxal ic acid to sequestering agent is significant in balancing speed of metal removal to ac¬ compl ish surface finishing against etching from exces¬ sively aggressive metal removal inasmuch as both the materials used contribute to metal removal. Experimen¬ tation ith variations in the ratio of acid to seques- tering agent have sho n that, as a general matter, Increasing the quantity of sequestering agent In rela¬ tion to acid increases the speed of metal removal and also increases the l ikel ihood that metal removal causes a distinctive "frosty" appearance which is deemed et- ching and which experience has shown must be pol ished before satisfactory plating can be accom l ished. Whi le the mechanism leading to such results is perhaps. not ful ly understood, it is bel ieved l ikely that the varying

concentrations cause varying rates of effectiveness of metal removal in the microscopic level "peaks and val¬ leys" or roughnesses of the co ponents. Where etal removal is essential ly the same in both areas, a frosty finish results. Where metal removal occurs more heavi ly at the peaks, a greater s oothness is achieved and the f inished component is ore acceptab le. Depending in part upon the specific ferrous al loy being worked, ra¬ tios of acid to agent in the range of from about 0.70 part to 1 part to about 0.20 part to 1 part have been found acceptable and are contemplated by this invention. A preferred range is about 0.25 part to 1 part.

In the l iquid dispersion composition, the chemi¬ cal s present as the acid and possib ly those chosen as sequestering agent(s) are not readi ly soluable in ater. Thus the dispersion which enables handl ing as a l iquid is aintained by the use of a suspending agent. The suspending agent must be a materiel which acts as a gel l ing and suspending agent in salt dispersions, and two usefu l maierici s are xanthan gum and t e proprietary l ine of materials sold by D.F. Goodrich Chemicals under the name Carbopol.

In use, the compositions of this invention nay be used in any kno n type of wet abrasive finishing equip- ment capab le of ithstandin the corrosive effects of the dispersions which result. Examples of such equip¬ ment are I isted in the prior patents ! isted above, and may include open and closed tu bl ing barrels, spinning

machines, vibrating machines, and spindle achines. Such equipment may be capable of batch processing, con¬ tinuous or flow through processing, or both. Solutions used may be batched or recirculated. The choice of such ^' equipment fs left to the ski l l of the person ski l led in the appl icable arts and learning of this Invention. Ho ever, as brou ht out more ful ly herein¬ after, e preferred- process uses apparatus arranged for flow through operation. As briefly mentioned above, a method of preparing ferrous metal components for subsequent surface electro¬ plating In accordance with this Invention Includes the known steps of preparing a dispersion conteining an acid and a sequestering agent, immersing the components and abrading media In the dispersion, and agitating the compo¬ nents and the abrading media while maintaining the com¬ ponents and the media immersed in the dispersion.

As practiced, a desired quantity of components are loaded into the treatment vessel and washed by flowing water through the vessel. The rinsing flow is stopped, and a flow of the dispersion is begun, preferably using a peristaltic pump to achieve a etered flow. After some I terval of time (on the order of about 10 to 60 minutes ⁾ , sufficient treatment composition has been added to the ater retained in the load to begin the "cutting" action, and at that time water flow is intro¬ duced. Preferably, the water flow mixes with the treat¬ ment composition before the dispersion thus formed enters

the treatment vessel. The starting of water flow may be determined by time (as suggested above) or by monitoring the pH of the spent dispersion l eaving the f low-through treatment vessel. The flow of treatment composition and water is then continued for the interval of time neces¬ sary to accompl ish the desired finishing action for the components, typical ly on the order of 20 to 150 minutes. During this interval of time, the pH of spent dispersion l eaving the treatment vessel shou l d be in the range of from about 6.0 to about 7.0.

A ter the components have reached a es ired finish, the flo of weter is greatly increased (on the order of ten times) hi le the flow of the treatment composition is decreased (on the order of 70 ) . With such relative -flow rates, the dispersion hich has been functio in as a finishing composition functions as a cleaning composition and cleans from the components any remaining residue of the ferric/ferrous sodiu /ammonium cxalεtes which have been formed during the f inishing stsge.

It is to be noted that an a'p parent factor in the successful operation of compositions as contemplated by this invention arises out of the differing solubi l ities of sodium and ammonium oxalates and the ferric/ferrous sodium/am onium oxalates formed w en the compositions are added to the treatment vessel s i n hich ferrous components are being finished. The latter materials are significantly more hi hly soluble in ater, contributing

to the finishing action sought and accompl ished by this I nventIon .

Certain experiments conducted in the development of this invention are reflected in the fol lowing exani- p 1 s .

Examp I e 1 Using a three cubic foot volum vibretory fi¬ nishing vessel and open end wrenches as ferrous compo¬ nents to be finished, the components ere rinsed as described above and a dispersion as then Introduced which had the fol lowing formula:

Constituent Weight percent Water 43.73

Oxal Ic aci 15.86 Di ammonium 1 .59

Phosphate

Tetrasod.ium 13.59 pyrophosphate suspending 12.80 acent surfactant 0.45

The treatment composition as fed i to the apparatus usi ng a peristaltic pump and at a f l o rate on the order of 0.5 ounce per minute. About three minutes after the dispersion f low was begun, water f low through the vessel as begun at about 1.0 gal l on per hour, ith the ater f low and dispersion f low being del ivered through a com¬ mon p ipe for pre- mix ing before reach i ng the vessel. F i n ish i ng of the com onents conti ued for about one

hour, during which time water and dispersion flows were manipulated to attain and maintain an effluent pH in the range of from about 5.8 to about 6.3. The components attained a bright and shiny finish. The flow of disper- sion was then stopped and water flow increased to about 10 gal lons per hour until the drain water ran essential¬ ly clean.

E amp I e 2 A load of sockets for socket wrenches were run ith a pyramid form edia in a ten cubic foot volume vibratory finishing vessel. The dispersion introduced had the for ula:

Constituent Weight percent

Water 48.8 Oxal ic aci 20.0

Phosphate

Tetrasod i um 13.7 pyrophosphate suspending .3 agent surfactant 1.5

The treatment compos ition as f ed i nto the apparatus us i ng a per ista l tic pump and at a f l ow rate of about 0.66 ounce per i nute. About ten i nutes after the dispersion f lo was begun, water f lo through the vessel as begun at about 1.2 ga l l on per hour, ith the water f low and dispersion f lo being del ivered through a co ¬ mon p i pe for pre- ixi ng before reach ! rg the vesse l . Fi ishing of the components continued for about one hour

and twenty minutes, during which time water and disper¬ sion f lows ere manipulated to attain and maintain an eff luent pH In the range of from about 5.5 to about 6.3. The components attained a bright and shiny finish. The f low of dispersion was then stopped and water f low Increased to about 2 gal lons per hour unti l the drain water ran essential ly clean.

Ex a p 1 3 A process simi lar to that of Example 2 as run using a dispersion having the f rmulation:

ConstI tuent Weight percent ater 42 suspen ing 15 agent

D i amp.on i urn 12

Phosphate p'onoa non i urn T2

Phosphate

0χa l ie ac I d 10

Tetrasod i urn 8.5 pyrophosphate surfactant 0.5

The increase in suspending agent made this dispersion much thicker. However, operation and results were es¬ sential ly similar to Example 2 above.

Example 4 A dispersion was prepared using l iquid phosphoric acid as a phosphorous source and ammonium hydroxide and sodium hydroxide as sodium sources. The dispersion was prepared to a formulation of:

Const i tuent W ight percen

Phosphor I c acid 4

Ammon i urn 24 hydrox i de

Oxa l ie ac i d 12

Water 9.5

Sodium hydroxide 6 suspend i ng 3.5 agent surfactant 1

The dispersion was suppl ied through a peristaltic pump in a anner si i l ar to that of the examp les above. Ho ¬ ever, the feed rates of dispersion and water were ad¬ justed In relation to one another and to the number of square inches of ferrous metal surface to be pol ished. With the pol ishing action establ ished as described above in Examp l e 1, the feed ^" rates of- d i s per s i σn/nvater were adjusted to be 0.66 lb/hour of dispersion and 2.25 lb/hour of ater for each one thousand square inches of surface being treated. Results achieved ere substan¬ tial ly those of the prior exa ples. Further, the re- suits were reproducible from run to run.

The experiment of Exampl e 4 as extended to ex¬ plore the range of ratios of dispersion to water in which reproducible results were achieved. It was dis¬ covered that a ratio of dispersion to water del ivered may range over ratios of from about 0.3:1 to about 0.9:1 whi le reproducib le resu lts are obtai ned. The range appears to ref lect the particular dispersion formul a

fol lowed, with a consistently fol lowed dispersion formu¬ la achieving reproducible results where the feed rates used were also adjusted so that a consistent total flow rate as measured against the metal area being pol ished was maintained at about 3 lb/hour per one thousand square inches of metal area being treated.

Whi le the examples here included wi l l reflect the parameters varied in experimentation done during devel¬ opment of the present invention, the forms of the pre- sent invention preferred at the writing of this descrip¬ tion are a l iquid dispersion hich has as Its consti¬ tuents those l isted In Example 4 hereinabove.

In the specification there have been set forth preferred embodi ents of the invention and, although specific terms are used, the description thus given uses term I no I cgy in a generic and descriptive sense only and net for purposes of l imitation.