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SSat man avia as a awarar ar.Kettes. N N: aAAAACsy A, GZOAAS NA s : RN A... 6 YSSSSSSSSSa gram ATTORNEY 2,812,240 United States Patent Office Patented Nov. 5, 1957 2 through valvcd pipe 39 to pump 41, by which the mixture 2,812,240 is forced through pipe 42 and vertical section 43 back inio the lower end of reactor . Heat is supplied by PROCESS OF MAKING BORON NITRIDE In eans of the elix 45 to keep the vertical section 43 at Alfed R. Globus, Forest Hills, N. Y., assignor to United a temperature above the melting point of the metal. ternational Research, Inc., a corporation of New The nitrogen introduced with the boron trichloride should be at least Sioichiometrically sufficient to react York with the horon prescrlt in the trichloride, with formation Application February 17, 1955, Serial No. 488,920 of boron nitride (BN). In practice a substantial excess 1 Claim. (C. 23-191) O of nitrogen will he used to insure completion of the de sired reaction and the maintenance cf a nitrogen atmos This invention is a new and useful process of making phere in the free space in the upper cnd of reactor 1. boron nitride and will be fully understood from the fol The boron trichloride will react immediately with the lowing description read in conjunction with the drawing allininum, with production of aluminum chloride (AlCl3) in which: and boron, which boron reacts immediately with the Fig. 1 is a diagrammatic, vertical section through ap nitrogen present forming boron nitride. The aluminum paratus in which the invention may be carried into effect; chloride which is in gas phase passes on into the con 3. denser 25. The boron nitride which is in solid phase Fig. 2 is a plan view of the apparatus which appears, collects as a layer of powder on top of the liquid aluminum in f eferringin Fig. to the1. figures, reactor 1 comprises vertically 20 and after sufficient has accumulated, will flow continu oriented tubular section 2 carrying top closure 3 and ously over into the collector 13. This collector is held bottom closure 4. Reactor 1 carries refractory lining 5, at a temperature above the sublimation temperature of preferably of bauxite brick or bonded alumina, Top aluminum chloride by the circulation of a heating fluid closure 3 carries manhead 6. A liquid, for example, a in jacket 18 to ins: Tc that the aluminum chloride will metal in liquid phase, may be supplied to the interior of 25 not condense at this point. The boron nitride which reactor 1 by introducing it into the top of riser 7 con accumulates in the collector 13 may be intermittently re sisting of tubular shaf 8 provided with refractory lining moved through the manhead 17 or through a gate valve 9 connected through horizontal pipe 10 provided with which may be connected to the cover of the manhead. refractory lining 11 communicating with the base of Condenser 25 is held at a temperature below the sub reactor 1. Reactor 1 is connected through side outlet 30 limation temperature of aluminum chloride by the cir 12 with collector 13. The collector comprises a verti culation of a cooling fluid through jackct 30. The alu cally oriented tubular section 14 carrying top closure 15 minum chloride may be intermittently removed from the and cone bottorn 16 provided with manhead 17. The condenser 25 through manhead 29. closure may be held at a predetermined temperature by Any residual nitrogen will pass on out of the con means of the jacket 18, into which a fluid may be intro densers throl'gh pipe 34 comingling in pipe 37 with that duced through the waived pipe 19 passing off through simultaneously introduced through valved pipe 51. Any valved pipe 20. The collector 13 carries baffle 21 ver unreacted boro trichloride passing out of the condensers tically oriented as indicated. Collector 13 discharges through pipe 34 wiil comingle in double elbow 38, with through outlet 23 connected to pipe 24, which is part of additional boron trichloride simultaneously introduced condenser 25. This condenser comprises vertically ori 40 through valved pipe 54. The amount of nitrogen intro ented tubular section 26 carrying top closure 27 and duced through valved pipe 51 and the amount of boron cone bottom 28 provided with manhead 29. Condenser trichloride introduced through valved pipe 54 are coordi 25 may be held at a predetermined temperature by means nated to maintain the desired reaction velocity in re of jacket 30 into which a fluid may bc introduced through actor 1 and to naint in an excess of nitrogen in the valved pipe 31 passing off through valved pipe 32. Con reactor to insure that the boron produced will react com denser 25 is provided with baffle 33 centraly positioned 45 pletely or substantially completely to the nitride. as shown. Material passes off from condenser 25 through Process| claim: of ?naking baron nitride which comprises main outlet 34 discharging into pipe 35, which is in turn con taining a bcdy of altiminism in liquid phase in a reactor nected to T 36 (Fig. 2). T 36 is connected through connected to it collector, which collector discharges into valved pipe 37, which in turn is connected to double 50 a condensei, contacting said aluminum with a mixture elbow 38. From double elbow 38 the valved pipe 39 of boron trichloride and nitrogen by passing said mixture passes downwardly discharging into pump 41, by which upwardly through the Sante, therely generating aluminum fluid may be forced through valved pipe 42 back into chloride in gas phase and a layer of boron nitride in solid the base of reactor 1. The vertical section 43 of this phase, condicting away the aluminum chloride so formed pipe carries insulation 44 within which is mounted the 55 in vapor phase and continuing the process until the helix 45, by which the vertical section 43 may be in boron nitride blows into said collector, maintaining said ductively heated to prevent metal solidifying at this point. collector it is temperature above the sublination point Referring to Fig. 2, T 36 is connected to valved pipe of aluminum chloride, maintaining said condenser at a 51. The double elbow 38 is connected horizontally to tenperature below the siblimation point of aluminum valvedIn operation pipe 54. the manhead 6 in reactor 1 is unplated chloride, removing boron nitride fronn said collector and and a burner is inserted through the same by means of renoving aluit in in chloride fronn said condenscr. which the interior of the reactor is heated to a red heat. Simultaneously nitrogen is introduced through valved pipe References Cited in the file of this patent 53 to purge the condensers of any oxygen initially pres UNITED STATES PATENTS ent. Following this manhead 6 is closed and aluminum 5 1,241,796 Weaver ------Oct. 2, 1917 in liquid phase is introduced by pouring it into riser 7 2,313,410 Walther ------Mar. 9, 1943 in amount sufficient to fill the reactor almost up to the 2,685,501 Spevack ------Aug. 3, 1954 point at which it would overflow into the collector 13. Following this the introduction of nitrogen through OTHER REFERENCES valved pipe 51 is continued and boron trichloride in gas 70 Kroll: "Zeitschrift fir Anorganische and Allgemeine phase is introduced throigh valved pipe 54. These Chemie," vol. 102, part 1, pages 17-25 (1918). comingle in the double elbow 38 passing downwardly

- t t UNITED STATES PATENT OFFICE - i. CERTIFICATE OF CORRECTION Patent No. 2,812,240 November 5, l957 Alfred R. Globus It is hereby certified that error appears in the printed specification ofPatent the aboveshould numberedread as patentcorrected requiring below. correction and that the said Let Gers Column l, line 27 for "shaf" read -- shaft --; line 48, for 'T 36 (Fig. 2). T 36" read -- tee 36 (Fig. 2). Tee 36 --; line 57, for "T 36" read -- tee 36 -; column 2 line 57, for "blows" read -- flows --. Signed and sealed this 24th day of December 1957.

(SEAL) Attest:

KAR. H. AXLINE ROBERT C. WATS ON Attesting Officer Commissioner of Patents