United States Patent [19] [11] Patent Number: 4,492,764 Watanabe et al. [45] Date of Patent: Jan. 8, 1985

[54] SINTERED CERAMIC BODY CONTAINING 4.022.584 5/1977 Rudy ...... Sol/98 4.145.213 3/1979 Oskarsson et al 75/238 TITANIUM CARBONITRIDE 4.268.582 5/1981 Hale el al...... 75/238 [75] Inventors: Tadahiko Watanabe, Saga; Yuko Primary Exam1'ner——Mark Bell Tsuya, Tokyo; Yuji Enomoto. Attorney. Agenl. 0r Firm-—Brisebois & Kruger Sakura, all of Japan [57] ABSTRACT [73] Assignee: Agency of Industrial Science and Technology, Tokyo. Japan A refractory ceramic body having excellent bending strength and high hardness and with little porosity is [21] Appl. No.: 475,976 ‘ obtained by a powdery mixture comprising 5 [22] Filed: Mar. 16, 1983 to 95% by weight of a titanium carbonitride and 95 to [30] Foreign Application Priority Data 5% by weight ofa metal boride such as metal diborides, e.g. , W3B5 and M0385 at a tempera Jul. 12, 1982 [JP] Japan ...... 57-121748 ture of 1700m to 1800° C. Further improvements can be [51] Int. Cl.3 ...... C04B 35/56; C048 35/58 obtained by partial replacement of the above mentioned [52] US. Cl...... 501/87; 501/96 components with elementary , titanium carbide or [58] Field of Search ...... 501/87. 96; 75/238. titanium nitride or when the titanium carbonitride com ‘ 75/244 ponent is a combination of at least two kinds oftitanium carbonitrides having different chemical compositions [56] References Cited relative to the proportion of the and nitrogen. U.S. PATENT DOCUMENTS

3.741.733 6/1973 Kieffer ...... 75/238 16 Claims, N0 Drawings 4,492,764 1 2 titanium carbide TiC, titanium nitride TiN or elemen SINTERED CERAMIC BODY CONTAINING tary boron. When elementary boron is added to the TITANIUM CARBONITRIDE powdery mixture, the amount thereof should not ex ceed 10% by weight. 7 BACKGROUND OF THE INVENTION 5 The admixture of the titanium carbide or nitride to The present invention relates to a novel sintered ce the binary mixture of the titanium carbonitride and the ramic body based on or containing a titanium carboni metal boride has an effect to impart a further improved tride or. more particularly, to a sintered ceramic body Hp hardness of, for example, 2500 kg/mm2 or higher at containing a titanium carbonitride and a metal boride room temperature to the sintered body in comparison and having excellent bending strength and hardness as with the sintered bodies prepared from binary mixtures well as outstandingly high density. of the components (a) and (b) alone. Similar improve Titanium carbonitrides are promising as a material for ment in the hardness of the sintered body is also ob various sintered ceramic bodies usable as a cutting tool, tained when the component (a) is a mixture composed parts of heavy-duty machines and the like since the of at least two kinds of titanium carbonitrides having sintered ceramic body based on or containing titanium different chemical compositions relative to the propor carbonitride is excellent in the high melting point, hard tions of carbon and nitrogen. ' ness and tenacity as well as the remarkable resistance against oxidation when used in a high temperature oxi DETAILED DESCRIPTION OF THE dizing atmosphere. PREFERRED EMBODIMENTS Notwithstanding the above mentioned advantages, 20 The first of the essential components, i.e. component titanium carbonitride-containing sintered ceramic bod (a), in the powdery mixture to be sintered is a titanium ies are currently not used in the industry at least as a carbonitride which is a chemical entity expressed by the refractory material because a sintered ceramic body formula Ti(CaN,3), in which the ratio of (1:8 should be prepared from a titanium carbonitride alone is relatively in the range from 10:90 to 90:10 or each of the values of brittle and has an unsatisfactorily low bending strength 25 a and ,B should be in the range from 0.1 to 0.9, n+3 while this problem of brittleness and poor bending being approximately equal to l. The titanium carboni strength cannot be overcome even by the attempts to tride should be in a powdery form having an average admix one or more of additive ingredients to the com particle diameter as ?ne as possible or, desirably, not position to be subjected to sintering due to the counter exceeding 2 pm. Such a product of titanium carboni acting adverse effects on the advantageous properties tride is commercially available. inherent to the titanium carbonitride. For example, The second of the essential components, i.e. compo titanium carbonitrides are useful as a matrix material of nent (b), is a metal boride selected from the group con cermets as sintered with metallic nickel as a binder but sisting of the MB; type metal diborides including tita such a titanium carbonitride-based cermet is defective 35 nium diboride TiBz, chromium diboride CrB2, tantalum due to the decreased resistance against oxidation and diboride TaBg, manganese diboride MnBZ, molybde poor heat resistance as a result of admixture of the me num diboride MOB2, vanadium diboride VBZ, tallic nickel. Therefore, it has long been desired in the technology diboride NbBZ, HfBz, aluminum dibo of ceramics to develop a sintered ceramic body based ride AIBZ and ZI‘B2, of which tita on or containing titanium carbonitride and having high nium diboride TiBz is preferred, and M2B5 type metal bending strength and hardness without suffering de borides including tungsten boride W1B5 and molybde crease in the resistance against oxidation and heat resis num boride M0285. The metal boride should also be in a powdery form having an average particle diameter as tance. ?ne as possible, preferably, not exceeding 2 pm or, SUMMARY OF THE INVENTION 45 more preferably, not exceeding 0.5 um. The above An object of the present invention is to provide a named metal borides may be used either alone or as a novel and improved sintered ceramic body of high combination of two kinds or more. melting point having excellent bending strength and The powdery mixture to be subjected to sintering hardness as well as high density due to the absence of should comprise from 5 to 95% by weight of the com any porosity without suffering decrease in the resistance 50 ponent (a) and from 95 to 5% by weight of the compo against oxidation and heat resistance as prepared from a nent (b). Although typically the powdery mixture is powdery mixture comprising a titanium carbonitride as composed of the components (a) and (b) alone, i.e. the an essential ingredient. total amount of the components (a) and (b) is substan Thus, the sintered ceramic body of the invention tially equal to 100% except impurities, the essential developed as a result of the extensive investigations 55 requirement is that the total amount of the components undertaken by the inventors, in which a large number of (a) and (b) should be at least 50% by weight, the bal powdery ceramic materials have been tested as an addi ance, if any, being titanium carbide TiC, titanium nitride tive to a titanium carbonitride with the above described TiN or elementary boron. When the powdery mixture object, is a sintered body of a powdery mixture com is composed of the components (a) and (b) alone, the prising (a) from 5 to 95% by weight of a titanium car 60 amount of the component (b) should preferably be in bonitride and (b) from 95 to 5% by weight of at least the range from 20 to 70% by weight so that further one metal boride selected from the group consisting of improvements are obtained in the bending strength, MBZ type metal diboride, e.g. diborides of titanium, hardness and density of the sintered body prepared chromium, tantalum, manganese, molybdenum, vana from the powdery mixture. When the amount of the dium, niobium, hafnium, aluminum and zirconium and 65 component (b) in the powdery mixture is smaller than M3B5 type metal borides, e.g. W2B5 and Mo2B5, where 5% by weight or in excess of 95% by weight, no satis the total amount of the above described components is factory results can be obtained in respect of the bending at least 50% by weight with the balance, if any, being strength of the sintered body. 4,492,764 3 4 The powdery mixture composed of the components belonging to the IVb group of the Periodic Table, the (a) and (b), optionally, with addition of a third compo metal constituent of the boride may react with the IVb nent, which may be titanium carbide, titanium nitride or element to form a layer ofa compound of the metal and elementary boron as mentioned above, is thoroughly the IVb element having good lubricity on the surface of blended in a suitable blending machine to obtain inti the machine part. mate contact between particles of the components and a Following are the examples to illustrate the present mold ofa desired form made of, for example, graphite is invention in further detail. In the examples, the chemi ?lled with the powdery mixture which is subjected to cal composition of each of the titanium carbonitrides is sintering by heating in an atmosphere of vacuum or a given by the formula Ti(CaN;;) with substitution of neutral or reducing gas such as nitrogen, argon, hydro respective numerical values giving the molar propor gen and oxides of carbon under a die pressure of 50 to tion of the carbon and nitrogen for the suffixes Cl. and B, 300 kg/cm2 at a temperature in the range from l500° to such as TI(CO_5NQ,5). 2000° C. or, preferably, from l700° to 1800° C. for a EXAMPLE 1 length of time of 10 to 200 minutes into a sintered body. Alternatively to the above mentioned so-called hot (Experiments No. l to No. 28) press method, it is of course optional that a green body Powdery mixtures were prepared each by intimately is ?rst shaped by compression of the powdery mixture mixing one of the titanium carbonitrides Ti(CQ,3N0_7), at room temperature followed by sintering without die Tl(CQ_5N()_5) and Ti(C0,7N0_3) and one or more of the pressure or a so-called HIP. process is undertaken. metal borides indicated in Table 1 below in the weight As is mentioned before, it is sometimes advantageous 20 proportion also indicated in the same table. The total that the powdery mixture contains a third component amount of the titanium carbonitride and the metal bo which may be titanium carbide TiC, titanium nitride ride or borides was equal to 100% in each of the pow~ TiN or elementary boron B so that a further improved dery mixtures. hardness is obtained in the sintered body assuming that A graphite mold was ?lled with the powdery mixture the sintering conditions are the same. For example, a Hv 25 which was then compressed in the mold under a die hardness of 2500 kg/mm2 or higher can be obtained by pressure of 200 kg/cm2 with heating at a temperature in the incorporation of a substantial amount of titanium the range from 1600° to 2000“ C. indicated in Table l for carbide provided that the total amount of the titanium 30 minutes to effect sintering. The atmosphere of this carbonitride and the metal boride or borides is in excess hot-press sintering was vacuum in all of the experiments of 50% by weight. The amount ofthe elementary boron when not mentioned otherwise in the footnotes of the should be limited not to exceed 10% by weight in the table. The Experiments No. 14 and No. 16 were under~ powdery mixture to be sintered. taken by ?rst shaping the powdery mixture at room Quite unexpectedly, it has been discovered that im temperature followed by sintering of the shaped green provements in the hardness of the sintered body can be body at l850° C. for 2 hours in an atmosphere of argon obtained also when the component (a) of the titanium 35 without die pressure. carbonitride is not of a single composition relative to The thus obtained sintered bodies were subjected to the values of a and ,8 in the but is a the measurements of the bending strength and the Vick mixture of two kinds or more of titanium carbonitrides ers hardness I-Iv at room temperature to give the results having different compositions from each other relative shown in Table 1. Further, a section of each of the to the proportion of carbon and nitrogen. In order to sintered bodies was examined by use of a scanning elec take substantial advantage of the above mentioned use tron microscope for pore defects in the structure. The of a mixture of titanium carbonitrides, the amount of results of this porosity examination are given in Table l each of the titanium carbonitrides should be at least by the marks A, B and C corresponding to complete 10% by weight in the powdery mixture to be sintered. absence, presence of a small number and presence of a As is described in the above, the sintered bodies of the 45 large number of pores, respectively. present invention are advantageous in their excellent Experiments No. 6 and No. 13 were undertaken for bending strength, high hardness, high density and very comparative purpose with omission of the metal boride dense structure as well as high resistance against oxida to give sintered bodies having a large number of pores. tion so that they are very useful as a material for cutting Heating of the above prepared sintered bodies ac tools and heat-resistant and wearing-resistant parts of cording to the invention carried out in air indicated that heavy~duty machines with very wide applicability. In no oxidation took place up to a heating temperature of particular, the metal boride component in the sintered lOOO° C. while the sintered bodies heated at 1200" C. body is effective in improving the sliding performance were found to be covered with an oxide film though or decreasing the friction of a machine part made insignificantly. thereof because, when the machine part is used in an environment containing a compound of the element TABLE 1 Sintered body Sintering Hardness Formulation temper- Bending Hy at room Exp. Titanium Metal alure. strength. temp. No carbonitride boride “C. kg/mm2 kg/mmZ Porosity l 70‘?! Ti(C(|_5N()_5) 30% TiB] 1600 ‘)3 B Z " " 1700 l 10 1. 00 A 3 i800 90 2350 A 4 1900 so A 5 " 2000 70 A 6 mos; THCOfNOjl — 1700 60 C 7 ‘)0’? TllCUjNUj) l0’7r TiB; 1700 71 A 4,492,764 5 6 TABLE l-continued Sintered hodv Sintering Hardness Formulation temperv Bending H. at room Exp Titanium Metal ature. strength. temp. No carbonitride horide “C. lt'g/mm2 lag/mm2 Porosity 8 80‘? Ti(C0.5N0.5) 209? TiBg 1700 84 A 9 60% Ti(C0_5Nt).s) 40’71 TiB; 1700 100 2350 A 10 4071 Tl(CQ_5N05) 6097 T18; 1700 104 2400 A 11 20% Tl(CQ__iN()_§l 80‘7? TiB; 1700 71 13 12 10% Ti(C(t5Nu,5) 90% TiBg 1700 54 C 13 1009? TitCogNrml -— 1700 51 C 14 70% Ti(C0_3N0f) 30% TiBg 18504 90 A 15 70C} Ti(Cr)_3N0_1) 30% T183 1700 97 2050 A 16 60% Ti(C()_;N0_7) 40% TiBg 1850“1 75 A 7 701-7( TitcojNojt 30% TiB; 1700‘ 110 2300 A 18 70% Ti(C()_7NQ_3) 30% TiB; 1700 110 A 19 50% TllCQSNQS) 50% NbB; 1800 36 A 20 55‘?! Ti(C(),5N0.5) 45‘71 CrB; 1800 80 2300 A 21 129? Ti(C0_5N0,5) 88% W385 1800 74 2200 B 22 65% THCOjNQj) 30% TiBg 1700 110 2300 A 5% T382 23 " 30% TiBg 17001 110 A 5% CrB1 74 67% THCMNM) 30% T113] 1700 110 A 3% VB: 25 65% Ti(C<145N0,5) 30’)? TiBg 1700 105 A 5% M083 26 " 30‘7r TiBg l700 Q5 A 5% Ht'Bg 2", ' 30% TiBg 17003 90 A 5‘; ZrBg 28 66% Ti(C0V5N0,5) 30% TiBg 1700 110 A 1% T3133 1% CI‘B] 1% M0335 1% W385 1sintered in an atmosphere of carbon oxide. {sintered in an atmosphere of nitrogen. *‘Smtered in an atmosphere of hydrogen. ‘Green body shaped without heating was sintered in an atmosphere of argon These sintered bodies according to the invention EXAMPLE 2 have resistance against oxidation as high as in the sin (Experiments No. 29 to No. 36) tered bodies prepared in Example 1 according to the invention. In this case, the total amount of the titanium carboni tride and the metal boride, i.e. titanium diboride TiBZ, in EXAMPLE 3 each of the powdery mixtures was not equal to 100% (Experiments No. 37 to No. 43) and a third component which may be elementary boron, titanium carbide TiC or titanium nitride TiN was ad Powdery mixtures were prepared each by intimately mixed as the balance in an amount indicated in Table 2 mixing two kinds or more of the titanium carbonitrides below. Experiment No. 34 was undertaken for compar Tia-‘101N039! Ti(C0,3N0t7), Ti(Co.5N0.5) and “((3071303) ative purpose with omission of the titanium carboni with at least one kind of the metal borides indicated in tride. The procedure for sintering of the powdery mix Table 2. Experiment No. 41 was undertaken for com ture was substantially the same as in Example 1 by the parative purpose with omission of the metal boride. techniques of hot-pressing. 50 Experiment No. 43 was carried out by the procedure of The sintered bodies thus obtained were subjected to the green body shaping at room temperature followed the measurements of the bending strength and Vickers by sintering free of pressure at the indicated tempera hardness at room temperature as well as to the micro ture for 2 hours in an atmosphere of nitrogen. scopic examination of the porosity in the same manner Table 2 also includes the results of the measurements as in Example 1 to give the results shown in Table 2, in 55 of the bending strength and Vickers hardness at room which the marks A, B and C for the evaluation of poros temperature and the porosity examination undertaken in ity each have the same meaning as in Table 1. the same manner as in Examples 1 and 2. The oxidation resistance of the here prepared sintered bodies was as good as those in the preceding examples. TABLE 2 Sintered body Sin' Hardness Formulation tering Bending Hrat room Exp. Titanium Metal temp. strength. temp‘. No. carbonitride boride Others “C. lt'g/mm2 kg/mm2 Porosity 29 68% Tl(C(J_5N()_5) 30% TiBg 2% B 1700 110 A 30 15% Tl(C()_5N()_5) 35% T1133 50% TiC 1900 60 A 31 35¢’! Ti(C0_5NQ_5) 35’71 T182 30% TiC 1900 70 2500 A 4,492,764 . 7 8 TABLE l-continued Sintered bodv Sin- Hardness Formulation tering Bending H.‘ at room Exp. Titanium Metal temp.. strength”. temp..7 ' No. carbonitride boride Others "C. kg/mm- kg/mm- Porosity 32 55% Tl(C()4§NQ5) 35% TiBZ 10% TiC 1900. 70 A 33 60% Ti(C0,5N0.5) 35% TiBz 5% TiC 1900 70 A 34 — 35% TiBZ 65% TiC 1900 50 A 35 64% Ti(C0.5N0_5) 35% Till; 1% TiN 1800 70 A 36 55% Ti(C0_5N045) 35% TiBg 10% TiN 1803 80 A 37 30% Ti(C0'5N0,5) 40% TiBg — 1700 100 2500 A 30% TKCQJNOJ) 38 40% Ti(C0,5N0>5) 20% TiBg -— 1700 70 A 40% Ti(C0.3N0.7) 39 20% Ti(C0_5N0_5) 60% TiBg — 1700 100 2600 A 20% Ti(Co.3No.v) 40 10% Ti(C0v5N0_5) 80% TiBz — 1700 70 B 10% Ti(C0.3N0t7) 41 30% Ti(C0_5N0.5) - -— 1700 50 C 30% TKCOJNOJ) 42 10% Ti(C0,1N0.9) 35% TiBg — 1700 100 2500 A 20% Ti(C()_3N0_7) 2% TaBZ 20% TKCOjNQj) 3% M0385 10% Tl(C0.7NQ.3) 43 30% Ti(C0,5N0‘5) 30% TiB; 10% B man 110 2500 A 30% TKCOJNOJJ ‘See text. dery mixture has an average particle diameter not ex What is claimed is: 25 ceeding 2 um. 1. A titanium carbonitride-based ceramic body pre 9. The titanium carbonitride-based ceramic body as pared by sintering a powdery mixture consisting essen claimed in claim 1 wherein the amount of the metal tially of boride in the powdery mixture is in the range from 20 to (a) from 5 to 95% by weight of a titanium carboni 70% by weight. tride, 30 10. A titanium carbonitride-based ceramic body pre (b) from 95 to 5% by weight of at least one metal pared by sintering a powdery mixture consisting essen boride selected from the group consisting of tita tially of nium diboride TiBz, chromium diboride CrBZ, tan (a) from 5 to 95% by weight of a titanium carboni talum diboride TaBZ, manganese diboride MnBz, tride. and molybdenum diboride MoBz, vanadium diboride 35 (b) from 95 to 5% by weight of at least one metal VBZ, niobium diboride NbBg, hafnium diboride boride selected from the group consisting of tita HfBZ, aluminum diboride AlB; and zirconium dibo nium diboride TiBg, chromium diboride CrBg, tan ride ZrBg, tungsten boride W2B5 and molybdenum talum diboride TaBg, manganese diboride MnBg, boride Mo2B5, molybdenum diboride MoBg, vanadium diboride (c) from 0 to 10% by weight elementary boron, and VBZ, niobium diboride NbBg, hafnium diboride (d) from 0 to 50% by weight of titanium carbide or HfBZ, aluminum diboride AlB2 and zirconium dibo titanium nitride. ride ZrBg, tungsten boride WZB5 and molybdenum 2. The titanium carbonitride-based ceramic body as boride M0385. ' claimed in claim 1 wherein the metal boride is titanium 11. The titanium carbonitride-based ceramic body as diboride TiBZ. 45 claimed in claim 10 wherein the metal boride is titanium 3. The titanium carbonitride-based ceramic body as diboride TiBg. claimed in claim 1 wherein the powdery mixture con 12. 'The titanium carbonitride-based ceramic body as tains elementary boron in an amount in-the range from claimed in claim 10 wherein the component (a) in the 1 to 10% by weight. powdery mixture is a combination of at least two kinds 4. The titanium carbonitride-based ceramic body as 50 of titanium- carbonitrides having different chemical claimed in claim 1 wherein the powdery mixture con compositions relative to the proportion of carbon to tains titanium carbide or titanium nitride in an amount nitrogen. up to 50% by weight. _ claimed13. The in titaniumclaim 12 carbonitride-basedwherein the amount ceramic of each body of the 5. The titanium carbonitride-based ceramic body as claimed in claim 1 wherein the component (a) in the 55 titanium carbonitrides is at least 10% by weight in the powdery mixture is a combination of at least two kinds powdery mixture. of titanium carbonitrides having different chemical 14. The titanium carbonitride-based ceramic body as compositions relative to the proportion of carbon to claimed in claim 10 wherein the titanium carbonitride in nitrogen. the powdery mixture has an average particle diameter 6. The titanium carbonitride-based ceramic body as 60 not exceeding 2 um. claimed in claim 5 wherein the amount of each of the 15. The titanium carbonitride-based ceramic body as titanium carbonitrides is at least 10% by weight in the claimed in claim 10 wherein the metal boride in the powdery mixture. powdery mixture has an average particle diameter not 7. The titanium carbonitride-based ceramic body as exceeding 2 pm. claimed in claim 1 wherein the titanium carbonitride in 65 16. The titanium carbonitride-based ceramic body as the powdery mixture has an average particle diameter claimed in claim 10 wherein the amount of the metal not exceeding 2 pm. boride in the powdery mixture is in the range from 20 to 8. The titanium carbonitride-based ceramic body as 70% by weight. claimed in claim 1 wherein the metal boride in the pow 1k * 1k * ik UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT I4, 492 I 764 DATED :January 8, 1985 'NVENTUMS) :Tadahiko Watanabe et al. it is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected asshown below:

On the title page ‘assignee should read: —-(73) Assignee: Director-General Of The Agency Of Industrial Science and Technology --. Signed and Scalcclthis Twenty-?rst Day of May 1985 [SEAL] . Attest:

DONALD J. QIUIGG Arresting Officer Acting Commissioner of Parents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENTNO. 14 492 764 DATED :January 8, 1985 |NVENTOR(S) ZTadahikO Watanabe et al It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

On the title page .assignee should read: —-(73) Assignee: Director-General Of The Agency Of Industrial Science and Technology --. Signed and Scalcdthis Twenty-?rst D a y of May I 985 [SEAL] . A ttest:

DONALD J. QUIGG Arresting Officer Acting Commissioner of Parents and Trademarks