Document d7RpL2yjdy8Baor646NKKO5e

FILE NAME Allied Signal Bendix ASB DATE 1960 July 19 DOC ASB203 DOCUMENT DESCRIPTION US Patent - Frictional Material - 291 United States Patent Office 2.945.291 Patented July 19 1960 2 2,945,291 FRICTIONAL FRICTIONAL MATERIAL Thomas G. Ankeny Birmingham Mich and John W. Arnett Dayton Ohio assignors to General Motors Corporation Detroit Mich a corporation of Delaware Flled Nov. 28 1958 Ser No. 776,973 8 Claims Ct 29 182.5 This invention relates to friction materials and is particularly concerned with ferrous friction members for use as clutches brakes and the like This application is a continuation of applica- tion N. 540,842 540,842 filed October 17 1955 now abandoned An object of the invention is to provide a ferrous friction facing consisting essentially of iron graphite and molybdenum disulfide In carrying out the above object it is a further object of the invention to form the friction member from a sintered mixture consisting essentially of iron powder graphite and molybdenum disulfide wherein the graphite makes up between fifth and fourth of the weight of the member A still further object of the invention is to provide a ferrous frichen member whereinwherein the member consists essentially of graphite tanging between 2010 and 257 to weight molibdenum molibdenum disulfide between 27 and 65 b weight with mon making up substantially all the re- mainder Another object of the invention is to provide the furtous friction element as heretofore disclosed wherein the element is coexter vely bonded to strong metal sup porting member for facilitating mounting of the friction element More specifilc it is an object of the invention to provide a sintered ferrous friction facing consisting essentally of 20 graphite 5 molibdenum molibdenum disulfide with substantailly all the remainder being iron with or without small additions of modifying materials wherein said percentages are expressed on a weight basis Further objects and advantages of the present invention will be apparent from the following description reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown In the drawings Figure 1 is a view in perspective of a typical brake band Figure is a view in perspective of a clutch disc Figure 3 is a view in perspective of a clutch or brake disc for use in clutch or brake pack Figures 4 and 5 are charis showing a comparison between conventional and metallic brake linings in de- celeration tests Modern automotive developments have imposed extreme operating conditions on the conventional type of clutches and brakes are The friction surfaces of conventional clutches and brakes are usually composed of molded nonmetallic material such as asbestos cotton linters and the like bonded together with a synthetic resin such as a formaldeh de resin the mixture may also include friction fortifying materials This mixture of ingredients is molded into a brake band or disc surface which may be bonded or riveted to a metal support While these friction elements and facings are satisfactory under normal driving conditions it has been found that repeated stops from high speeds causes a tremendous overheating and eventual breakdown of the materials used in the brakes In most cases nonmetallic brake materials are not useful at temperatures above 750 F. and such temperatures are frequently exceeded in repeated high speed stops under extreme conditions Since the trend in automotive design is tov and heavier and for higher powered vehicles is apparent that the friction materials insed in the brake and church surfaces most be improved in order to keep up with the developIn ment of the industry It has been found that metallic friction materials offer an interesting field of development However most metallic friction materials while highly satisfactory for example in wet clutch applications are not useful for brakes since they tend to squeak and grab in the dry condition Furthermore due to the abrasion of the mate- rials in the dry condition much of the friction facing is abraded from the friction surface which in turn self- siguravates the wear condiven Karibamore the noisi- ness of these materials has made them unsuitable in the past for passenger vehicles There are however many advaarates in the use of metalle triction materials some of the more important being ability to withstand high temperatu conditions ability to withstand higher enga pi^,, sores and in most cases longer wearing characteristics We have developed a friction friction materid which overcomes these past disadvantages of met the fri on materials when used in the dry state and which has maintained 30 all of the advantages advantages of metalle facing materials We have found that our friction material when us in con junction with a diez or band type brake will outlast nonmetallic friction materie's many times and will not be deleteriously affected at the bish mperatures reached 35 during repeated high speed stops In tech went tests show that the present friction material will outwear several sets of conventional nonmetallic dosa of material under identical operating condition- Further wore the metalhe friction material does not exhibit the fade of trictional 40 qualities normally present in metallic materials when excessive temperatures are encountered Under actual road conditions the present friction material operates smoothly and silently throughout extended use In fact the facing material operated well under les's comprising 48 ten consecutive stops from . maximum speed of one hundred miles per hour a condition which could not be duplicated with nonmetalle nes which taled com pletely after three to fout of such stops Our new friction material is a sintered forrans material having varying degrees of porosity and made from a mix ture consisting essentially of men poeder poeder graphite and molybdenum disulfide to this buste rantite may be added small quantities of siltar and selami materials such as cademed mullite together with copper and lead = 5 for modifying the action of the friction material The friction material is preferably bonded to strong metal support through which it may be suitably secure to the brake or clutch mechanism in which is to be subse- quently used Due to the petence petence of large quantity of graphite the material does not have a high degree of flexibility and is not readily bendable and therefore the strong metal support such as a steel backing is generally backing preferred molyb- Specifically the m teha contains gr shite in quantities of from 20 to 25 25 by weight together with demum disulfide in quinces of trein % to 67 by weight with substantially all the reminder being iron The material is made by mixing the ingredients in finely divided form wherein for example the aton powder ranges between 150 and 325 mesh 70 This mixture is then briquetted to the desired shape under briquetting pres- sures ranging from 40,000 to 100,000 pounds per square 2,065,901 inch preferably at 70,000 pounds per square inch The briquettes are next sintered for about 45 minutes at a tem- perature ranging between 1850 F. and 2050 F. under oxidizing conditions for example in detaydir we completely burned natural gas cracked ammonia or hydro- gm The resulting material presents a highly desirable friction material that will withstand high temperaturge maintain its frictional qualities over a wide range of tam- paratures and which is long wearing and quiet In most cases as to bond the previously stated it is desirable majerial to a strong backing member and this is accomplished by placing the briquettes upos supporting ibers of steel that have preferably been coated oonnttooppofoonene A number of another with these sandwiches are stacked suitable spacers therebetween and the bonding is accom witp h tl he si tacs k unh dereprd ea- eure. A procedure of this character is fully disclosed in Wellman Patem 2,178,527 weislwl ell knoiw n tn he art It is preferable to accomplish the sintering and bonding in a single operation although it is also possible to first ainter and then bond although It this case the briquettes are sintered between sheets of graphitic material or metal having a nonadhening refractory coating thereover Another modification of the process contemplates a presinter of the briquetted powder at a temperature in the order of 1600 F 10 1950 F. for a period of 30 to 45 minutes This partially siniers the briquette and makes it easier to handle The presintered briquette is than assembled with the backing member and is bonded in the usual manner at about 1750 F. for 30 minutes These conditions may vary for example the bonding tem- parature may be between 1750 F and 2100 F while Lie time may be between 20 minutes and 45 minutes varying inversely as the temperature During the bonding step the porous pan is completely sintered These variations widely in operating conditions may vary and are critical so long as a good sinter and bond is obtained not A preferred embodiment of the invernon comprises the following formulation Example 1 22 Acheson 38 graphite % molybdenum disulfide 100 mesh 74 250 mesh reduced oxide iron powder A mixture of this material is briquetted at 80,000 pounds per square inch and is sintered on a steel supporting member of the desired configuration which has a flash copper plate thereon for a period of about 45 minutes ai 1050 F under pressure whereupon the material forms a strong sintered layer coextensively bonded to the supporting member The fricuon and wear characteristics of this material may be modified by small additions of sulfur and ceramic materials such as mullite clays etc. In this case the sulfur is preferably combined with the iroo or may be an impurity therein and may range up to % by weight of the total mix This addition ap- pears to improve wear The ceramic material such as mullite may range up to 75 by weight of the total mix This addition acts as a friction modifying material and generally raises the coefficient of friction slightly In any caac these additions are optional and should not exceed a total of % by weight of the element It is understood that in many cases the effects of sulfur and caramica can be attained without adding any material to the mix In these cases reduced oxide iron powder may be chosen which contains sulfur and insoluble ceramic material within the ranges noted as impurities therein Similarly small additions of lead and or copper may be added to modify friction characteristics as is well known in the art For example copper up to % by weight and or lead up to % by weight may be added These modifications prove useful under certain conditions Our invention however is directed specifically to the basic formulation of a high percentage of graphite 20 to 25 ) with molybdenum disulfide in controlled amounts wherein the remainder of the element consists essentially of iron with or without the modifying ingredienu set forth berein Some specific examples of other mixes which are satisfactory are as follows wherein all percentages are expressed by weight Example 2 20 Acheson graphite % 150 mesh copper powder % 100 mesh lead powder % 100 mesh molybdenum disulfide .75 calcined mullite 15 66.25 100 mesh reduced iron oxide powder containing combined sulfur therein equal to 1 of the iron This mixture of powdered materials is briquetted at 70.000 pounds per square inch and may be sintered on a steel supporting member which has been copper 20 plated for a period of forty minutes at a temperature of 2050 F. in a nonoxidizing atmosphere under pressure The powdered matenal forms a strong sintered layer coextensively bonded to the supporting layer Example 3 22 Acheson graphute % 100 mesh molybdenum disulfide 74 250 mesh reduced iron oxide powder containing in combined form sulfur together with insoluble ceramic 30 material in quantities equal to about 17 and 75 re- spectively of the total mix The mixture of these powdered materials may be prepared and sintered as in Example 2 35 Example 4 20 Acheson graphite 25 200 mesh copper powder 4.5 100 mesh lead powder % 100 mesh molybdenum disulfide .75 sulfur .65 calcined mullite Remainder 100 mesh reduced iron oxide powder The same procedure for forming the material and sintering the same as in Example 2 may be followed Example 5 21 Acheson graphite % 100 mesh lead powder % 100 mesh molybdenum disulfide Remainder 250 mesh reduced iron oxide powder con- taining combined sulfur equal to about % of the total mix A mixture of this material may be formed and sintered as in Example 2 In the drawing several forms of the friction member described in this disclosure are shown For example in Figure 1 a conventional type of brake band 20 is shown which has a ferrous friction surface 22 and a metal supporting back 14. This band may be made as herein described by placing preformed friction layers 12 upon the preformed supporting members 24 and stacking the sandwiches under pressure in a suitable furnace for sintering Figure 2 shows one type of clutch plate at 26 45 which includes a splined hub 18 a steel disc 30 and friction surfaces 32 bonded thereto The friction surface 31 may be provided at both sides of the clunch as shown if desired Pigure 3 shows still another form of clutch or brake at 34. In this form the steel disc 36 supports a friction surface 38 at one or both sides thereof and the disc may splined be as at 40 on the outer periphery or as at 42 at the inner periphery thereof This type of plate is gen erally used in a pack wherein alternate plates are splined 75 at the inner and outer periphery respectively These 8,045,891 plates may be used in disc brakes for example as dis- closed in Lambert Patent 2,405,219 which shows one type of automotive disc bra'e bra'e or multiple plate clutches as disclosed in Almen and Carnegie application S.N. 392,396 now Patent 2,733,797 assigned to the assignee of the present invention The three curves in Figure 4 show consecutive stops at one minute intervals at 50 60 and 70 miles per hour with a commercial molded nonmetallic lining wherein the rate of deceleration is maintained at fifteen feet per second per second The fade characteristics of the lining are indicated by the increasing bydraulic pressures required to maintain constant deceleration Thus at 50 miles per hour the pressure required to maintain this deceleration varied from 490 pounds per square inch for the first stop to 855 pounds per square inch for the tenth stop At 60 miles per hour these figures were 560 pounds per square inch for the first stop and 1145 pounds per square inch for the tenth At 70 miles per hour the lining failed on the sixth stop By way of companson Figure 5 shows the same curves for our improved metallic lining as described herein and made in accordance with Example 1 I will be seen that the pressures required for the first stop are consistently lower and that the pressures required for subse quent stops are substantially constant No failures were noted All tests were made on identical equipment and with identical braking elements with the exception of the brake material per se In this instance the commercial lining tested was of a 408 square inch area while the 30 ferrous lining was only 36 square inches in area The present invention therefore is directed basically to a porous ferrous friction element including a relatively high percentage of graphite together with significant quanuues of molybdenum disulfide wherein said element may 30 30 or may not contain small additions of wear and friction modifying ingredients The friction element may also include an impregnant within the pores thereof if it is desired for sealing the pores against the ingress of the atmosphere where the material is to be stored over ap 40 preciable periods of time This material is preferably a heat resistant resin which can be impregnated into the material and which does not markedly influence the frictional characteristics of the matenal Therefore 11 15 understood that impregnants may be used without de- 45 parting from the concept of the invention Throughout this specification the term ceramic material is used together with mullite as one embodiment thereof It to be understood that this example is illustrauve only and that clays silica magnesium oxide mica or any of the other refractory ceramic materials may be used with varying useful results While the forms of embodiment of the present in- vention as herein disclosed constitute preferred forms it is to be understood that other forms might be adopted What is claimed is as follows 3. A new article of manufacture comprising a friction facing consisting essentially of a compacted and sintered body formed from a powdered mixture of 20 to 25 graphite % to % molybdenum disulfide and the balance iron 2. A new article of manufacture comprising a friction facing consisting essentially of a compacted and sintered body formed from a powdered mixture of 22 graphite % molybdenum disulfide and the balance iron 3. The article as claimed in claim 1 wherein the friction facing is coextensively bonded to a metal backing mem- , ber 4. The article as claimed in claim 2 wherein the friction facing is coextensively bonded to a metal backing mem- ber 5. A new article of manufacture comprising a friction facing consisting essentially of a compacted and sintered body formed from a powdered mixture of 20 to 25 graphite % to 67 molybdenum disulfide and the balance iron wherein the iron includes as impurities insoluble ceramic material up to 75 and sulfur up to % by weight of the powdered mixture 6. The article claimed in claim 5 including lead and copper in quantities less than % by weight each 7. new article of manufacture comprising a frie tion facing consisting of a sintered compact of graphite 20 to 25 molybdenum disulfide % to % sulfur up to 19 mullite up to 75 copper up to 5. lead up to 50 and the balance iron said quantities being expressed by weight 8 A new article of manufacture comprising a friz tion facide consisting of a sintered compact of graphite 20, copper 37 lead % molybdenum disulfide % calcined mullite 75 sulfur .67 and the balance iron said quantities being expressed by weight References Cited in the leof this patent UNITED STATES PATENTS 2.239.134 2.367,406 2.367,406 2.408.430 2,731.360 2.784,105 2,848,795 Wellman _-...222-2..2- Apr 22 Kott 2-2. eee .--..--2 Jan 16 Lowey et al --_ Oct , Love 2-2 eee _.-2--- Jan 17 Stedman et al ...-...- Mar 5. Lowey 28s ....-2.20.. Aug 26. 1941 1945 1946 1956 1936 1956 July 19 1960 Faxed Nov 26. 1958 T G ANKENY AL FRICTION MATERIAL 2,945,291 2 Sheets 1 G. G. Thomas G. NTUK NTUK Arkony John 11 Arnett John ...... John ...... ...... ...... THEIR ATTORNEY July 19 1960 Filed Nov. 29 1958 T. G. ANKENY ET AL FRICTION MATERIAL 2,945,291 Sheets Sheet L F DecelerationDeceleration 15 Ft/ * 4 bich 120Seuare LivngLiving FaileFdailed _ Per +: a COMCPHOMPHCOMPH q 10 0Pounds ne Dt anePresure 500 NEG Ne Presure - Y SOMPH SOMPH apt So300Lime Sigh Sigh tof. o tT 200l..tT tt 4ze 3 | Stops Stops 5 | <6 7? 00 3 10 } | Decleration Sec i Sec epe inch otrefe fp i |- ep 60MPH anne 1000Square rT t fet Tt Per ~ Pounds st To 70MPH Presure 7 E 9 Big.5Big.5 Big.5 opr Line 60 an Stops Tas ---------- Onkeny Tt ihs $a BYThomTahsomaTshomasWarnetWarneOtnkeny THEIR THEIR ATORNEY ATORNEY ATORNEY