【作者】 史晓亮；

【导师】 汤凤林； 段隆臣；

【作者基本信息】 中国地质大学 ， 地质工程， 2003， 博士

【摘要】 目前,国内冲击凿岩用的潜孔锤钻头、钎头以及牙轮钻头等,其切削具一般都采用YG类硬质合金柱齿,由于硬质合金的耐磨性相对较低,在钻进坚硬岩层时,钻头的寿命和钻进时效都很低; 金刚石超硬复合材料钻头具有较高的耐磨性,已被广泛地应用于钻井工程,但由于其抗冲击性能较差,不适于冲击凿岩钻进,只能用于回转钻进。砂卵砾石地层的钻进,一直是钻探工作者想要解决的难题,地层复杂,钻进过程中钻头即要承受岩石的磨损,又要承受岩石的冲击; 其他钻头及钻进方法应用效果也不十分理想,使用普通硬质合金球齿,对一般卵石地层有一定的适应性,但遇到大的漂石时,钻头切削齿损坏严重而不进尺。为了解决潜孔锤钻进硬岩以及砂卵砾石地层钻进的难题,研制一种具有较高耐磨性,同时又具有较高抗冲击性能的复合材料,来替代传统的硬质合金齿,是十分必要和迫切的。国内、外科技工作者对金刚石(CBN)—硬质合金复合齿进行了大量研究,并取得了一定的成果。但仍存在一定的问题:(1)如何解决金刚石(CBN)在高温热压烧结过程中的热损伤问题; (2)以廉价铁代替昂贵的钴作为粘结剂的胎体配方; (3)解决复合齿烧结模具的材质与结构优化设计问题,以降低复合齿加工成本,提高复合齿机械性能; (4)微量元素及稀土元素的添加方式、数量对复合齿性能的影响及作用机理。本文总结并综合分析了国内外金刚石、立方氮化硼烧结体的制造方法,在这些理论和导师的正确指导下,解决复合齿的结构、配方和制造工艺流程中的难题,利用低温活化热压的方法,成功研制了金刚石(CBN)—硬质合金复合齿,利用金刚石与立方氮化硼表面金属化,解决了高温热压烧结时对金刚石的热损伤问题以及金刚石、立方氮化硼与基体结合包镶问题,同时通过合理添加稀土方式和添加量,基本解决以铁代钴复合齿技术难题。由于金刚石(CBN)是非金属,与一般金属或合金间有很高的界面能,即使在较高的温度和压力下,金刚石表面也不能被低熔点金属或合金所浸润,小颗粒的金刚石只是仅仅机械被包镶于金属胎体中,而不是被冶金焊接,其粘接性差。由于金刚石(CBN)—硬质合金复合齿的烧结温度在1050℃左右,对普通金刚石的热损伤严重,大大影响了复合齿的性能。本文通过金刚石(CBN)表面采用镀覆技术(真空蒸镀W、化学镀Ni-W-B、Ni-W-P)解决了上述难题,使复合齿的性能得到了保证和提高。通过对超硬复合齿烧结模具的结构和材料优化设计,大大降低了复合齿的加工成本,提高了其机械性能,有利于优化烧结参数(烧结压力、烧结温度、保温保压时间)和复合齿结构的优化。陶瓷烧结压头的使用相对于石墨压头,模具寿命提高了20多倍,复合齿加工模具成本降低超过了100%,同时使复合齿的抗弯强度、磨耗比、抗冲击韧性大大提高,更多还原

【Abstract】 At the present, the cutters used in button bits, rock bits and roller bits are mainly cobalt tungsten carbide in our country. Because of their low abrasive resistance, the bit service life and drilling efficiency were very low when the hard and extremely hard formations were being drilled. Owing to its high abrasive resistance, the diamond composite material is widely used in drilling operations. However, its toughness against impact is too low to be used in percussion drilling, only can it be used in rotary drilling. Drilling in the gravel formation is the problem that drilling engineers want to overcome, complex formations make bit endure not only wearing and tearing of rocks but also impacting of rocks. Other drilling methods are not good for this kind of formation, and common tungsten carbide button bit is fit for ordinary gravel formation, but when encountering big rock whose diameter is bigger than diameter of drill hole, cutting button can’t penetrate. In order to solve the problems encountered by DTH hammer in hard rock drilling and gravel formations, make bit life longer, increase rate of penetration and decrease drilling cost, it is necessary and urgent to develop a new type composite material with high abrasive resistance and high toughness against impact. Although there are a lot of studies on diamond and cubic boron nitride enhanced tungsten carbide composite button, and some productions are achieved, but there are some problems such as: Firstly, how to solve the heat corrosion of diamond during the process of sintering at high temperature and pressure; Secondly, studying on matrix of substituting cheap iron for costly cobalt; Thirdly, how to solve material and structure designing of sintering mould, in order to reduce machining cost of composite button and improve mechanical performance of composite button; Fourthly, adding modes & quantity of minim element and rare earth, and its effecting mechanism. This paper summarizes and analyzes the making methods of diamond, cubic boron nitride sintering body, and on basis of these theories and tutor’s right guidance, it solves the problems of structure, directions and making techniques, by the sintering method of low temperature activation hot-pressing, diamond and cubic boron nitride enhanced tungsten carbide composite button is successfully made. By coating on diamond and cubic boron nitride, it solves the problem of heat corrosion of diamond, combined problem of diamond, cubic boron nitride and matrix, in the same time, by reasonable adding mode and quantity of rare earth, it solves technical problems of substitute iron for cobalt composite button. As diamond and cubic boron nitride are non-metal and there are very high boundary energy between diamond and cubic boron nitride and matrix or ally, so diamond and cubic boron nitride surface can’t be sintered by low melting point metal or alloy, with bad bonding between diamond and cubic boron nitride and metal matrix. Because the sintering temperature of diamond and cubic boron nitride enhanced tungsten carbide composite button is about 1050℃, ordinary diamond will suffer serious heating corrosion, then affecting performance of composite button. This paper uses coating technology of diamond and cubic boron nitride such as vacuum metal deposition, chemical coating Ni-W-B, Ni-W-P to solve these problems, and makes performance composite button assure and improve. By optimized designing on structure and material of super-hard composite button, it reduces making cost of composite button, and improves the performance of composite button, then is in favor for optimize sintering parameters such as sintering pressure, sintering temperature and time of keeping pressure and temperature. Life-span of ceramic sintering pressing rod is more 100 times than Life-span of graphite sintering pressing rod, and the mould cost of composite button reduces 600%, bending strength, wear ratio, toughness against impact improve greatly, then it is in favor for realizing rare earth and substitute iron for cobalt of composite button. Because of lack of cobalt resource, it is very important to substitute iron for cobalt. Rare earth that is called industrial monosodium glutamate has been applied successfully in improving material performance. But rare earth is seldom applied in heat-pressing diamond tools or diamond composite materials. The main reason is that rare earth is very easily oxidized during the process of ball grinding, in the same time adding quantity of rare earth is very little, it is very difficult to assure rare earth evenly dispersed, technology repeating and stability. So, expect rare earth middle alloy powder, adding modes of rare earth oxide, carbide, chloride, hydride, nitride and etc. are washed out. But directly adding mode of rare earth middle alloy powder has good effect, such as the patent of RE-Cobalt middle alloy powder is applied successfully in producing tungsten carbide was reported. Rare earth middle alloy powder solves the problem that rare earth is evenly dispersed in metal felting materials. The cost of producing rare earth middle alloy powder is very high, and the price of common middle alloy powder is about 2000yuan/Kg, other middle alloy powders need be made specially, then it is the main factor that restricts rare earth middle alloy powder be applied directly in heat-pressing diamond composite material. This paper adopts direct adulterating method to do adding rare earth experimentation; in the same time do some experiments of matrix of substituting iron for cobalt composite button, and gains success. Bending strength, wear ratio and toughness against impact of some kind of substituting iron for cobalt composite button achieves and indeed exceeds the performance of common super hard composite button. Testing results on laboratory condition show that its hardness is more than HRA88, equals to conventional tungsten carbide, and that its abrasive resistance is 10~40 times than conventional tungsten carbide, and its most toughness against impact is more than 200 Joules, its least toughness against impact is more than 120 Joules. Therefore, theoretically, this super hard composite body has very high mechanical properties that can meet the need of percussion drilling, and can solve the problems encountered with conventional tungsten carbide button bit and drilling in complex gravel formation. The results during the process of drilling on micro-drilling experiment station, field practical drilling in gravel formation, drilling in drilling hall, drilling on percussion drilling station and field percussion drilling show that compositebuttons and its bits meet drilling needs. During the development, I have optimized the formula and sintering parameters of the super hard composite body. Its optimum sintering temperature is from 1050℃ to 1060℃, the optimum pressure of graphite sintering mould is from 40MPa to 55MPa and the optimum pressure of ceramic sintering mould is from 60MPa to 80MPa, and the optimum sintering time from 3 minutes to 5 minutes. Upon the thorough analysis on diamond & cubic boron nitride enhanced super hard composite button, substituting iron for cobalt super hard composite button, and indoor & field drilling experiments of composite button bits, it shows that: Firstly, using technology of coating on diamond surface, there is crystal abnormity area between diamond and matrix, linking mode of diamond surface and crystal abnormity area is microcosmic inlaid mode, and it has strong resistance to diffusing of carbon element, and then protects diamond very well; in the same time makes diamond and matrix alloy have high combined strength, improves toughness against impact of composite button. Secondly, because of adding boron mode of chemical coating cobalt & boron, it make boron element disperse evenly in super hard composite button, and reacts with carbon in diamond surface to form B4C that enhanced diamond crystal interface. In the other hand, boron can react with cobalt to form chemical compound that reduces the presence of single-phase cobalt in super hard composite body system, and then improves the thermal resistance of the super hard composite body. Thirdly, because of adding phosphor mode of chemical coating cobalt & boron, it make phosphor element disperse evenly in super hard composite button, phosphor, nickel & phosphor alloy adsorbing on the surface of nickel and cobalt grains, the surface energy of these particles is decreased largely, this made it possible to sinter tungsten carbide cobalt hard metal at low temperature; Fourthly, according to powder metallurgy pressing theory, and combining with practical studies of diamond & cubic boron nitride tungsten carbide, this paper designs reasonable sintering mould of composite button, then improves life-span and low making cost of mould, and make composite button density & rigidity be improved. By optimizing sintering mould, it assures that sintering parameters optimization and improving performances of super hard composite button. The ceramic pressing rod can support more than 100 million Pa even if the sintering temperature is at 1100℃, but graphite pressing rod can support 20 to 50 million Pa, resisting intensity of pressure of ceramic pressing rod is very higher than graphite pressing rod; Substituting conventional mould for optimized mould, it assures the performance of composite button and low making cost. Fifthly, substituting iron for cobalt lows the cost of composite button, and solves the practical problems in the strategic altitude. Sixthly, diamond & cubic boron nitride enhanced tungsten carbide and rare earth substituting iron for cobalt composite button bits of reasonable formula can solve drilling problems in gravel formation and skidding formation, the bits have good performance of high penetration and longlife-span. Seventhly, the toughness against impact, wear ratio of diamond & cubic boron nitride enhanced composite button of adding diamond & cubic boron nitride of vacuum coated tungsten is higher than using uncoated diamond & cubic boron nitride. Eighthly, diamond & cubic boron nitride enhanced composite button has good economical and social benefits. In general, this paper combines coating technology of single crystal diamond and cubic boron nitride, substituting iron for cobalt formula, rare earth & microelement adding mode, optimizing designing of sintering mould, optimizing parameters reasonably, then improves the performances of composite button and low the making cost; it studies from theory to practice and gains some practical results. Room and field drilling experiments and analyzing & testing technology show that super hard composite button have predominant performances.更多还原