Search Documents

A brief introduction is given of the scale and of some special features of South African gold mining; it is noted that great depth of mining and narrowness of the reefs, and hardness and abrasiveness of the rock are the main sources of the problems of the industry. The most inhibiting problems are: Excessive rock pressure occcurring in conjunction with rockbursts, hot and humid working places due to high virgin rock temperature and auto-compression of the air, and low level of productivity. Conventional solutions applied ordinarily in mining do not promise to eliminate, or even alleviate, these difficulties.

Jan 1, 1985

By F. G. BREYER

ZINC metallurgists continue to follow with keen interest reports of successful results from the continuous retort plants at Palmerton, Pa., and Meadowbrook. W. Va. The new process had already demonstrated its ability to reduce the lead content of the metal and to effect savings in labor and fuel. The past year has shown that the retorts themselves can he built to last long enough so that the retort cost per ton of metal is lower than in past practice with small horizontal re- torts. A number of the latest type of retorts are reported to have been in continuous operation for over 18 months without a failure and are said to be still in good condition. This seems a complete answer to the last question which remained before continuous zinc smelting could he pronounced commercially practicable.

Jan 1, 1932

By W. M. Weigel

The first successful use of the wire saw in slate quarrying in the United States was late in 1926, at the quarry of the Colonial Slate Co. near Wind Gap, Pa. This installation was sponsored and supervised by the United States Bureau of Mines in collaboration with the National Slate Association.' The success of this trial resulted in other installations of wire saws, so that 27 were in operation at Pennsylvania slate quarries2 by October, 1928. Marble Quarrying with a Wire Saw Until recently, little or no attempt has been made to use the wire saw in the quarrying of other stone, but it is believed that its successful use in slate will be followed by attempts to take advantage of its possibilities in other quarrying operations. An example of such a trial is the recent installation of a wire saw at the marble quarry of the Saint Clair Marble Co. near Guion, in the Ozark region of northern Arkansas. This quarry is in a comparatively new district and the decision to open and develop it had to be made in the face of many unknown factors. For this reason, it was essential that the development costs be held at a minimum, and as a wire saw could be installed more cheaply than standard channeling equipment, it was decided to try it out. One factor Largely controlling the decision was that the location was peculiarly adapted to this method. The point of development selected was on the rather abrupt end of a ridge formed on the south by an almost perpendicular bluff along the White River and on the north by a rather steep slope with little or no overburden. By taking advantage of this topography it was possible to place the supporting standards for the sheaves at both the outer and driving end without the necessity of drilling or excavating openings to receive them, and to locate the motive power in line with these standards, which made it unnecessary to deflect the sheaves.

Jan 1, 1931

Spectrum Resources commenced operations as a public listed mining company in August, 1983, with a variety of precious metal projects in New Zealand. At that time the outlook for most mineral commodities, with the notable exception of precious metals, was decidedly gloomy. Metal prices were depressed and demand forecasts were universally gloomy. Against this background the company reviewed the non-traditional metals sector to try and identify a 'new' metal with an above average demand growth and market value. Lithium, a commodity with exciting new applications in storage batteries and alloys, met both criteria. Annual world consumption of lithium is around 7000 tonnes; current prices are around $NZ40/lb for lithium metal and demand growth is projected at five to seven per cent per annum. Geothermal fluids at Wairakei and elsewhere contain anomalous amounts of lithium and in May, 1984, the Chemistry Division of DSIR was commissioned to carry out a literature survey on the possible recovery of lithium and other minerals from geothermal waters. The survey results were encouraging and the company subsequently negotiated exclusive access rights, for research purposes, to geothermal discharge fluids from the Wairakei and Kawerau geothermal fluids. Most of the subsequent investigations reported here were carried out by Chemistry Division, DSIR, under contract to the company with some assistance from the Industrial Processing Division, DSIR.

Jan 1, 1986

By E. L. Howard, R. S. Barney back

E. L. Howard (Chief Testing Engineer, Pacific Cement & Aggregates, Inc., San Francisco, Calif.) We have made concrete with all the materials mentioned by Mr. Barneyback, including sawdust. He has highlighted the principal problems and effects found when these light materials are used as concrete aggregate. We can only agree with the inter-relationship he has emphasized between grading, specific gravity and unit weight. Uniformity in these characteristics helps to assure good concrete. Mr. Barneyback says the design of lightweight concrete mixtures "is a complete mystery to most engineers". He is wholly right in his evaluation of our ability generally to put together a concrete using lightweight aggregate. A study of the references he has appended will yield little comfort in the matter of proportioning. Much remains to be done in this area of concrete. We believe Mr. Barneyback has treated the subject, though briefly, in an excellent manner.

Jan 1, 1965

By Roland B. Hoag, Roger G. Webber

Sulphate concentration in groundwater is a good measure of the extent of oxidation of sulphides, provided that sulphide minerals are the primary source of the sulphate. A study was conducted near the Eustis Mine in Quebec to determine where and how the sulphate in groundwaters originated. Atmospheric precipitation is the only source of sulphate other than oxidation of sulphides, and in this study area it is equal to 0.01,. millimole per litre. The oxidation of sulphides can be divided into subsurface oxidation (mainly inorganic processes) and surface oxidation (including both organic and inorganic processes) . The maximum sulphate concentration due to subsurface oxidation of sulphides depends on the solubility of 0 2 in water and is 0.25 millimole per litre. Surface oxidation is, therefore, responsible for any amount greater than atmospheric plus subsurface contributions (0.29 millimole per litre). Surface inorganic oxidation occurs in waters with a pH greater than 15 and is controlled by the kinetics of the oxidation processes. Organic (bacterial) surface oxidation is dominant only in acid (pH< 1.5) waters. The bacterial action accelerates the oxidation of sulphides, and large quanttties of sulphate may be introduced into solution.

Jan 1, 1976

By Boxun Lu, Juan Wei, Kun Chen, Wanlin Wang, Lejun Zhou

"Slag system is an indispensable part during the continuous casting process, and playing various important roles like absorbing inclusions, modifying heat transfer rate, preventing oxidation of molten steel, etc. to ensure the smooth process and excellent slab quality. However most slags contains more than 8% fluorides which tend to introduce a series of environmental and health problems. This study involves the research of the removal of fluorine through the chemical composition optimization. Through the studies of CCT, DHTT, XRD and SEM, it has been successfully founded that the crystalline phase of Ca11Si4B2O22 discovered in this study shows very similar crystallization property as Cuspidine (Ca4Si2O7F2), which is the most important crystalline phase in the current fluorine bearing slags. Moreover, the optimized free/low fluorine slag shows the opportunity to replace conventional high-fluorine mold slag for casting medium carbon steels that is regarded as the bottleneck of green slag development for continuous casting.IntroductionMold flux has been widely used in continuous casting to control heat transfer, lubricate the strand, absorb inclusions, provide insulation and prevent oxidation of the molten steel[1-3]. It usually contains fluorides, like CaF2, NaF etc., which are used to control the viscosity and solidification temperature of mold fluxes [4-5]. However, the presence of fluoride leads to corrosion of equipment, serious environmental pollution (toxic volatiles and water pollution), and high processing cost of cooling water[6-7]. Therefore, the study of low or free fluorine mold flux is of interest and attracts worldwide attention.S. Y. Choi et al. [4] used B2O3 as a substitute for cuspidine in steel B2PB2) however, B2O3 content was extremely high (up to 30 w%). Other studies have investigated F-free mold flux by adding or optimizing components as MgO, Li2O, B2O3 et al[8-11]. However, most of these focused on the melting and viscosity issues or for low or ultra-low carbon steels, where crystallization tendency is not significantly strong. Very few studies regarding to the development of low/free Fluorine mold flux for casting medium carbon (MC) steels have been conducted, due to the difficulty of the crystallization and heat transfer control without the formation of cuspidine."

Jan 1, 2014

By Michael Twomey, Alastair Torrance, Alan Twomey

Low density explosives have been available in various forms for nearly 20 years. These initially consisted of various diluted forms of ANFO formulated to slow the rate of reaction. One such product that was developed was a blend of ammonium nitrate and rubber. This product uses a coarse fuel provided by granulated rubber to slow the reaction rate of the explosive rather than being a diluted form of ANFO. There has always been a technical difficulty in blending two dissimilar materials without subsequent segregation.

Jan 1, 2011

By P Krauss, S Harpalani

Methane emitted from underground coal mines, along with ventilation air and known as ventilation air methane (VAM), constitutes the largest component of coal mine methane (CMM) emissions. Atmospheric methane, on the other hand, is a potent greenhouse gas with a significant adverse impact on the atmosphere. This has led to the development of various technological alternatives for its use as an energy fuel. Techniques involving oxidation of VAM, usually consisting of very low concentrations of methane, have been validated in the past. Prominent among these technologies are the thermal and catalytic flow reversal reactors, ancillary fuel technologies, lean fuel gas turbines, and concentrators and gasifiers. However, the efficiency of any VAM utilisation technique depends on the amount and concentration of methane in the ventilation exhaust air. Therefore, quantification of VAM emission from a coal mine is the first step towards identifying the most suitable technology for its utilisation for energy production. This paper presents an evaluation of the efficacy of VAM as an energy source. It provides details of a case study aimed at developing a technique to accurately quantify VAM emission from a coal mine. It further discusses the various VAM utilisation techniques available, and presents an economic evaluation of the alternatives. Based on the findings of the study, the most feasible method for VAM utilisation is identified for the mine. The paper summarises the procedure for quantifying VAM emissions and selecting the most suitable utilisation technique.

Jan 1, 2005

Improve the safety and comfort of operators of large mining equipment. Approach Develop an improved driver restraint system that is easy to use, reliable, and cost-effective, while providing increased protection in the event of a collision or rollover. The Novel Restraint System There are several problems associated with conventional lap-belt type restraint systems. Among these are: restriction of movement, lack of comfort, and fear of entrapment. Standard seatbelts become dirty and oily from lying on the vehicle cab floor and can ruin a driver&apos;s clothes. Some haulage equipment may not even have seatbelts available to drivers since they are sometimes removed during maintenance activities or as a result of vandalism. Recognizing a need to address such problems by providing a more acceptable means of driver restraint, the Bureau of Mines designed and fabricated a novel vest-type restraint system. The vest is designed to be worn during a driver&apos;s 8-hour shift and would be issued much like safety glasses, hard hats and safety shoes, thus becoming part of the operator&apos;s individual protective equipment and assuring that each vehicle has a restraint system when in operation. The vest-

Jan 1, 1985

By J. A. Botin, K. H. Singh

INTRODUCTION The Alfredo underground mine is one of the three mining operations of Rio Tinto Minera, S.A., all near the community of Rio Tinto in Huelva province of southwest Spain. The other two operations are Corta Atalaya open pit (Pyrite ore) and Cerro Colorado open pit (Copper ore 1. Underground mining of Alfredo Mine for pyrites started in the nineteenth century and continued without interruption until 1979 when it was discontinued due to economical reasons. In 1972, a new project was started for the mining of copper bearing ores on the footwall of the pyrite deposit. This copper ore is locally named “Cloritas” and it forms a nearly vertical and tabular shaped orebody which forms an envelope at the footwall of the San Dionisio pyrite orebody. Mining of the Cloritas commenced in 1975 using cut and fill stoping. In 1977, the original project was completely revised which led to the introduction of a bulk mining system to achieve a planned production of 3,000 tonnes of ore per day. This paper covers the economic and planning aspects of the mine and discusses the evolution of the mining method for the Cloritas orebody. A GENERAL DESCRIPTION OF THE CLORITAS OREBODY The “Masa San Dionisio” (figure 1 ) is a massive sulphide orebody located in the town of Rio Tinto, about 90 kilometres west of Sevilla, Spain. Extensive vein-type sulphide mineralization exists in the volcanic host rocks of the Masa San Dionisio. Within this area of stockwork veins, there is a higher concentration of copper in the form of chalcopyrite in a zone adjacent to and paralleling the contact with the massive sulphides. This copper envelope is locally referred to as the "Cloritas Orebody” and the ore within it is called "Cloritas”. The main zone of the Cloritas orebody, (figure 11, is tabular and nearly vertical having a length of 375-400 m east-west, a thickness of 20-50 m north-south, and a vertical extension of 500 m from the surface. In addition to this area, there is a second less important low grade area called zone 2A located to the north of the main zone below 26 Level which, in some sections, is not fully separated from the main zone. MINING METHODS Mining in Rio Tinto area can be traced back to the Phoenecians and the Romans. Modern day mining started with the demand for sulphuric acid during the last half of the nineteenth century. By 1971, more than 33 million tonnes of pyrite had been mined out of Alfredo Mine, (San Dionisio Orebody), using labor intensive drift and fill methods and also by open pit method. During the last decade, underground mining of the pyrite had become uneconomic due to lower prices and a slackening demand for pyrite, and the underground mining operations for pyrite were finally stopped in 1979. In 1971, a major change in the long range mining plans for Masa San Dionisio was established. Between 1971 and 1975, underground mining of pyrites was progressively reduced while open pit extraction was increased in

Jan 1, 1981

By Todor P. Stefanov

The thermal draught within ventilation networks of underground mines depends to a great extent on the shafts depths and degree of change of ventilating air density. When the topology and space orientation of a ventilation network are constant, the dynamics of thermal draught is determined mainly by the variations of the heat- and mass-transfer processes in the openings. This conclusion follows from the well known basic theoretical notions about the thermal draught-aerostatics and thermodynamics [1]. Quantitative evaluation about the influence of heat- and mass-transfer processes on dynamics of thermal draught could be made through: direct mine measurements, special experiments and with the aid of mathematical models. The first two methods produce sufficiently accurative results, however it is very difficult to perform such studies, particularly when these processes are evaluated within a large scope and multifactor aspects. Mathematical models of thermal draught allow to overcome easily these difficulties. The degree of accuracy of results, obtained by this method, depends to a great extent on the degree of approximation achieved by the model to the real heat- and mass-transfer processes. In this paper, with the aid of Bulgarian developed method, algorithm and computer program V WT-4 - for complex evaluation of ventilation parameters in active mine ventilation networks [2], the authors investigate some changes in the thermal draught. Basically, the method is an iterating evaluation of an open set of equations, which represents relationships between the following basic parameters of a mine ventilation network: [ ]

Jan 1, 1980

By Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan, Joseph Toth

The difficulty in material characterization and the erratic response of cemented soil layers, such as caliche in the Las Vegas valley, creates challenges for practicing engineers to reliably predict the response of deep foundations. The focus of this paper is the numerical prediction of axial response in drilled shaft foundations, which are commonly used in infrastructure projects (i.e., bridges and tall buildings) in Las Vegas, NV. The prevalence of hard caliche layers with variation in the degree of cementation add to the complication in numerical modeling. In this study, the applicability of two existing t-z models, developed for Florida limestone and soft rock, was evaluated based on numerical simulations of three bi-directional load tests conducted at caliche-dominant sites. The corresponding top-down load tests were also simulated for further assessment. A MATLAB-based finite-difference program, NVShaft, has been used to implement the mentioned t-z models in axial load analysis. Complexity originating from drilled shaft construction and the interaction with caliche during one axial load test resulted in a stiffer predicted response compared to measure data. For the other two load tests, both t-z models produced comparable load-displacement responses. It was observed that the t-z model for Florida limestone predicted relatively stiffer responses and higher drilled shaft capacity.

Sep 8, 2021

By I. Nilsson, G. Sundkvist, A. Danielsson

A spectrochemical method of slag analysis is descibed which utilizes fusion of the sample with a flux, then cooling and crushing to put all samples into a common form. The powder, is then fed onto adhesive tape and passed through a spark by means of a special device to provide very reproducible discharge conditions. Combined with a direct-reading optical emission instrument, this system provides speed and accuracy of antilysis heretofore unobtainable for. slag samples by any other method. THERE are many suggested methods for spectro-chemical analysis of slags. The most important are fusion-pellet methods and solution methods. In our company the fusion-pellet method has been used earlier, and is described by Lounamaa. W. H. Tingle and C. K. Matocha have made refinements of the pellet method.&apos; A Committee of the British Iron and Steel Research Association has investigated different methods of spectrochemical analysis of slags. Its purpose was to formulate a method which would give the complete analysis in 30 min with an accuracy of ±3 pct. The committee recommends a solution technique, which was thought to correspond best to their requirements. The method to be described is a fusion-tape method. The sample is isoformed by fusion and grinding. The powder is analyzed with the tape technique. The tape machine and some of its applications are described earlier.4&apos;5 The powder to be analyzed is continuously fed onto a moving adhesive tape, which passes through the spark gap. The sparks break through the tape and vaporize and excite the material to be analyzed. The most outstanding feature of the tape machine is its very high reproducibility. The concept of isoformation has been introduced earlier.= It means a pretreatment of the samples to make them uniform from the spectralanalytical point of view, i.e., cancelling systematic differences between the samples. The purpose of the isoformation is to reduce the influence of particle size, as well as chemical and mineral composition. Before describing the isoformation by fusion plus grinding, which is the purpose of this paper, a few words will be said about two other types of isoformations, i.e., grinding with buffer and ion exchange plus grinding as they have been considered during the application of the tape technique for slag analysis. Grinding with buffer might be a sufficient isoformation in some special cases, where the mineral composition is defined. The time of grinding must, however, be rather long, at least 5 to 10 min, even when using such an efficient mill as the Swing Mill from Messrs. Siebtechnik, Mühlheim, Germany. This type of isoformation is not recommended due to its limitations and due to the fact that the gain in time compared with the fusion technique is almost negligible. The principle of ion exchange plus grinding and some of its applications have been described.5 The following elements of interest in slag analysis can be determined in this way: Na, K, Cu, Mg, Ca, Ba, Zn, Pb, Al, Cr, Mn, Fe, Co, Ni. The very important element Si, however, cannot be analyzed with this method. Although the ion exchange isoformation for slag analysis cannot be looked upon as a routine method, it can be used for

Jan 1, 1962

By H. D. B. Wilson

"IntroductionRECENT ADVANCES in geo-chemistry and in •our knowledge •of crystal structure provide a key which enables us to create a systematic picture of the genesis of many ore deposits. This genetic scheme may be used with confidence in assessing certain types of orebodies and may be of some aid in actual exploration, since it affords a rational explanation of the dependence of the composition •of the ore minerals on that of the rock type in which they occur with which they -are •associated. For purposes of the present paper, .the elements chosen are •chromium, vanadium, iron, and titanium. The oxides of all these metals occur in deposits of similar or related type, and it is proposed to show that, for each, the composition of the •ore mineral is related to •the composition of the enclosing :rock, and that one of the principal factors controlling the composition of the ore is the ionic size of its constituent elements.Geochemical PrinciplesThe crystals of the rock-forming silicates and of the magmatic oxide minerals are essentially ionic types. This means that they are composed •of oppositely charged ions such as Mg²+ and 0²-, which are held together by electrostatic attraction. The ions of each element are spherical, with characteristic size known as the ionic radius. Crystals are built up by the packing of these spheres in the most stable arrangement compatible with the size and the size and valence of the ions• involved.Many of the principles governing the formation of ionic crystals are •simple ,and logical."

Jan 1, 1953

By Mirko Jurkovic, Thomas Hueper, Jens Kempken

The high competition scenario pushes the steel producers business. Zero defect requirements from customers force the operators for additional efforts in process control and quality management. PQA® has been developed as an advanced process and quality management assurance solution. It is focusing on the analysis of process data, equipment information, inline quality measurement devices and trend analysis. The paper describes the structure of the advanced process and quality management assurance solution PQA®; it gives insights on the expert know-how, process and quality evaluation and points out the benefits like cost reduction, improvement yield and customer satisfaction increase.

Oct 1, 2019

By C. E. Lundin, D. T. Klodt

The binary alloy systems, Y-Ti, Y-Zr, and Y-Hf, have been investigated throughout their entire composition regions. There is no compound formation in any of the systems, and each system is characterized by a single eutectic reaction. The eutectic compositions and temperatures are as follows: A eutectoid reaction pct Y and 870°C occurs in the Y-Ti system, whereas a peritectoid reaction,: pct Y and 880°C occurs in the Y-Zr system. Peri-tectic-type reactions at temperatures above the eutectic levels are postulated for the yttrium and hafnium transfovmations. The development of the technology of yttrium has been given considerable attention during the past few years, and studies of binary phase equilibria have, of course, taken a prominent position in this development. In many respects yttrium, in the third group of metals of the periodic table, is similar to the adjacent group of metals, titanium, zirconium, and hafnium, and the knowledge of the phase relationships of yttrium with these metals is basic to their technology. MATERIALS AND EXPERIMENTAL PROCEDURES Materials. The metals for this investigation were supplied by the General Electric Co., Aircraft Nuclear Propulsion Department. The yttrium was in the form of an arc-melted ingot, and the other metals were in the form of high-purity, iodide-Process crystal bar. Table I lists the purities of these materials. Alloy Preparation. Melting was done by conventional techniques in a nonconsumable electrode arc furnace in an atmosphere of purified argon. Melting conditions for each binary system were the same. Each alloy button was inverted and remelted several times to assure homogeneity. Accurate weights of the charges and resultant alloy buttons were obtained to indicate deviations from intended compositions. No chemical analyses were obtained since melting weight losses were consistently in the range of 0.1 to 0.2 pct of the total weight. 10- or 20-g buttons for each 5.0 wt pct composition increment were melted to survey the three individual alloy systems. Additional alloys differing in composition by 1.0 or 0.1 wt pct increments were also melted to study selected regions of the systems. Metallograpllic Techniques. Standard metallo-graphic techniques were followed for mounting and rough grinding. Preliminary polishing was accomplished using 6-u diamond paste as an abrasive on a Metcloth Lap. Final polishing was done on a Microcloth-covered wheel using 1-u diamond abrasive paste. Purified kerosene was used as a lubricant for both polishing stages. • sothermal- Annealing. Alloys were sectioned for as-cast structlure examinations and then homogenized in preparation for isothermal-annealing treatments. Homo{:enization was accomplished by cold pressing the alloy buttons followed by 72-hr anneals at 1100c. The alloys were encapsulated in Vycor or quartz for the homogenization treatments or for isothermal anneals. Resistance-wound or resistance-element tube furnaces were used for the annealing treatments. The homogenized alloy buttons were cold rolled until cracking occurred or until a -in. specimen thickness was obtained. Small -in. square) specimens for the isothermal anneals were then sawed from the alloys. Each specimen was wrapped in tantalum foil before being sealed in the capsule. Temperatures during the anneals were controlled The time at temperature necessary to equilibrate the structures during the anneals was determined for each alloy system by holding triplicate specimens of alloys at a constant temperature for three different periotls. The specimens were quenched and examined microscopically to determine the number and amounts of phases present in the micro-structure as a function of time. Melting Studies. Eutectic temperatures of the three alloy systems were established from the results of incipient-melting studies conducted on as-cast alloys. Specimens to be melted were suspended on a tungsten wire inside a graphite cylinder placed in a glass vacuum chamber. An optical pyrometer was used to follow the temperature of the specimen as it was inductively heated in a high vacuum. The temperatures were corrected for emissivity losses by standardizing the pyrometer with known-melting-point metals. Accuracy of the temperature measurements is estimated to be + 10°C. The melting point of the yttrium was determined to be 1550°C by this technique. The invariant-temperature levels were also checked by an anneal-quench technique. This technique consists of annealing a series of

Jan 1, 1962

By R. W. Vander Laan

Conneaut has a long and illustrious history as a major Great Lakes port for coal and iron ore. The first dock was built in 1892 for unloading iron ore from the Mesabi Range for shipment to the Pittsburgh steel mills via the Shenango & Lake Erie Railroad, later to become the Bessemer & Lake Erie Railroad. The Pittsburgh & Conneaut Dock Company was incorporated in 1893. The world&apos;s first Hulett automatic ore unloader was constructed at Conneaut in 1899. Steam operated, it was the model for the giant electric Huletts used today, named after its inventor, George Hulett, who was a Conneaut resident.

Jan 3, 1974

By James A. Morrison, Stephane Carayol, Paul H. Madsen

The Rio Piedras Alignment Section 7 of the Tren Urbano is currently being constructed beneath a historic commercial section of San Juan. Different portions of the section are being constructed using open cut, cut-and-cover, New Austrian Tunneling Method (NATM), Earth Pressure Balance Machine (EPBM), and as tacked drift mined support system. The combination of complex geology, low ground cover, and several innovative construction methods present many challenges to the ground control program. Mining and construction sequences were first developed to minimize ground movements and risk of damage to structures. A unique compensation-grouting program was developed to improve the ground, limit settlement, and recover settlements incurred due to mining.

Jan 1, 1999

By Kan Song, Lin Liu, Hengzhi Fu, Jun Zhang, Haijun Su, Xiaojiao Jia

"Al2O3/YAG/ZrO2 eutectic in situ composite has been regarded as new generation of high temperature structural material due to its excellent performance even close to its melting point. The directionally solidified Al2O3/YAG/ZrO2 eutectic ceramics are prepared by recently developed Laser Floating Zone Melting (LFZM) apparatus in which a splitter mirror is used to obtain two beams with the same quality from one CO2 laser. With the two laser beams irradiate the sample from opposite directions, the sample is zone melted. The apparatus configuration and the solidification processing are described in detail. The solid/liquid interface morphology is studied and the mechanism of microstructure formation especially the characteristic of eutectic cellular is discussed. It is shown that YAG and ZrO2 phases play a leading role during the ternary eutectic growth. Meanwhile, the relationship between the solidification microstructure and the processing parameters are investigated.IntroductionAl2O3/YAG/ZrO2 ternary eutectic in situ composite, due to its excellent high temperature mechanical properties, is now considered to be a promising candidate material as a replacement of nickel based super alloy for new generation aero space engine turbine blade [1]. They exhibit flexural strength of 360-500 MPa from room temperature to 2073K in air atmosphere [2]. The compression creep strength at 1873K is 433MPa with the strain rate of 104/s [3]. However, because of the high melting point and complex physical properties, there remain still many difficulties for its application. One of the bottlenecks is the poor understanding of the relationship between microstructure and solidification conditions."

Jan 1, 2012