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Manganese oxides show high catalytic activity for CO and HC oxidation without including platinum group metals (PGM). However, there are issues with both thermal stability and resistance to sulfur poisoning. We have studied perovskite-type YMnO3 (YMO) with the aim of simultaneously achieving both activity and durability. This paper describes the oxidation activity of PGM-free Ag/i-YMO, which is silver supported on improved-YMO (i-YMO). The Ag/i-YMO was obtained by the following two methods. First, Mn4+ ratio and specific surface area of YMO were increased by optimizing composition and preparation method. Second, the optimum amount of silver was supported on i-YMO. In model gas tests and engine bench tests, the Ag/i-YMO catalyst showed the same level of activity as that of the conventional Pt/?-Al2O3 (Pt = 3.0 g/L). In addition, there was no degradation with respect to either heat treatment (700°C, 90 h, air) or sulfur treatment (600°C to 200°C, total 60 h, 30 ppm SO2).

AN outline is given of the work performed and the method of procedure followed in correlating test results on specimens of heat-treated S.A.E. chromium-vanadium steel 6130 as a basis for revision of the physical-property charts for certain automotive steels. Revision of the charts was proposed by the Iron and Steel Division of the Standards Committee of the Society, and a subcommittee, of which the author is a member, was appointed to carry on the preliminary work of revision. The paper is a report of the results of the tests made. Test specimens of S.A.E. Steel 6130, to be drawn at three different temperatures after quenching, were prepared by four steel manufacturers. These were distributed among 30 cooperating laboratories, which made a series of about 115 tests including complete chemical analysis, tensile-strength, and Brinell, scleroscope and Rockwell hardness tests on the specimens.

Mr. Jennings describes a test now being considered for determining the point of optimum superheat for lifting iron from a static to a dynamic condition, with tensile strength of alloyed cast iron of 80,000 lb. per sq. in. and of heat-treated iron of 100,000 lb. per sq. in. When this field is entered, increased temperature becomes necessary for consistent results, and a series of tests is being run to discover approximately the temperature at which breakdown of the carbon nucleus occurs. The electric furnace, Mr. Jennings asserts, offers a non-oxidizing and non-contaminating method of melting iron at any desired temperature and allows iron to become high-brow and choosy.

STANDARDS of accuracy in forging are subject to constant revision. Accuracy depends on the equipment used, and the limit of forging accuracy was thought to have been reached because of the structural limitations in machines of existing types. However, the development of a new type of pressure machine has again caused a revision of our ideas of the accuracy attainable. Finish forging on this machine can be done on the heat remaining from forging or annealing, at a temperature below that at which scale is formed. Cold coining is also done with this machine with a high degree of accuracy and uniformity. What may be referred to as pressure machining of forgings eliminates roughing cuts, reduces the number of handlings and, in some cases, entirely eliminates further machining. Other economies resulting from uniformity are the facility with which work fits into chucks, jigs and hoppers and the uniformity in weight of parts such as connecting-rods.

ACHIEVEMENTS of the last ten years in increasing the power-weight ratio of aircraft engines are stated and contributing factors are analyzed. Aluminum alloys have replaced cast iron and steel for certain parts, not entirely because of their lower weight but because of a combination of properties which better fit them for the task. Similar considerations must govern the replacement of aluminum-base alloys by those of magnesium. The most promising immediate field for the magnesium alloys is said to lie in applications wherein strength and lightness are the main considerations and high-temperature properties are of secondary importance. Properties of magnesium castings and forgings are compared with those of castings and forgings of the aluminum alloys. Features of design are discussed which should receive special attention when changing a part from aluminum to magnesium. Machining practices for magnesium are covered in some detail.

A grinding-machine for finishing spur-gears is illustrated and described; claims are made that it will grind transmission gears on a production basis after they have been heat-treated and will produce correct tooth-contour, smooth finish and accurate tooth-spacing, these features being necessary in producing gears that are interchangeable and that run quietly. This machine is of the generating type, its action being that of rolling a gear along an imaginary rack and using the grinding wheel as one tooth of the rack. The dished grinding-wheel is reversible, 30 in. in diameter, mounted below the gear, and can be swiveled to the right or left of the center position up to an angle of 25 deg. The work-spindle carries the indexing and the generating mechanisms at the rear, where they are accessible and yet are protected.

Periodically recurring problems of gear noise and wear which seem to arise from no specific cause frequently affect the manufacturing side of the automotive industry and especially the gear-manufacturers. While much has been written and discussed about the mathematics and geometry of gears, which should overcome all of these problems, the trouble unfortunately still persists. The paper outlines the experience of the organization with which the author is connected in solving a rather difficult problem that offered an opportunity for a more thorough analysis than did its predecessors. Laboratory and dynamometer analyses of the product showed that it compared favorably with the output, of other factories.

Stating that the production of satisfactory gears is one of the most serious problems confronting the automobile builder, the authors give an outline of the practice of producing gears that is used by the company they represent and describe a new method for cutting the rear-axle drive-pinion by using two machines, each machine cutting one side of the teeth. Explanations are given of the various steps in the process and the reasons for stating that this method is not only cheaper but produces gears of higher quality. Numerous suggestions are made for improving gears and axles, and the claim is made that it is doubtful if the spiral-bevel gear has had a fair chance because axles usually have not been designed so that the main consideration was the requirements of the gears.

After a brief historical review of the development of worm-gears, the author deals with worms and worm-wheels in detail, presenting the subjects of proper choice of materials, tooth-shapes, worm-gear efficiency, the stresses imposed on worm-gearing and worm-gear axles. Usually, he says, the worm is made of case-hardened steel of S.A.E. No. 1020 grade; however, when the worm-diameter is smaller and the stresses are greater, nickel-steels such as S.A.E. Nos. 2315 and 2320 grades are utilized. The worm should be properly heat-treated and carbonized to produce a glass-hard surface. Grinding of the worm-thread is necessary to remove distortions. Bronze is the only material of which the author knows that will enable the worm-wheel to withstand the high stresses imposed by motor-vehicle axles, and three typical bronze alloys are in common use.

After defining hypoid-gears and outlining their action, together with their general characteristics and advantages, the authors compare them specifically with spiral-bevel gears and follow this with a description of how the axis of the pinion is offset from the axis of the gear and how the direction of the offset determines whether the spiral is right-handed or left-handed. Considering pitch-lines, details of the mesh between a crown-gear and an offset pinion are presented, since this constitutes a special case of hypoid-gearing, and the application of these principles to a pair consisting of a pinion and a tapered gear is discussed. The rate of endwise sliding, the proper ratio of gear-diameters, tooth loads and tooth profiles are other phases treated specifically, and computations of surface stresses by the Hertz formulas, with special reference first to a comparison between helical teeth and straight teeth, and then with reference to hypoid-gears, are outlined.

In this paper the author gives the results of an investigation of coarse crystallization. This investigation was carried out with commercial materials such as cold-drawn wire, hot and cold-rolled sheet, strip steel, cold-drawn tube and cold-pressings. The results of other investigations are briefly outlined. Coarse crystallization, or grain-growth, it is stated, is due to the action of a limited amount of strain, exceeding the elastic limit, followed by annealing within certain temperature ranges. The experimental work which led to this conclusion is explained in detail in the paper. The effect of forging, cold-drawing, cold-rolling and cold-pressing was determined with commercial materials. Some study was made of the effect of carbon on grain-growth and of the effect of coarse crystallization on the physical properties. In the discussion of commercial materials special reference is made to those used in motor car construction.

The author states that the purpose of the paper is to outline that phase of metallurgical work pertaining to the connection between the laboratory and production in the automotive industry. Reasons are cited for selecting certain designs for parts to facilitate machining, complete or partial case-hardening, finishing and assembling. The next step is the choice of materials, a subject which is treated at some length. The author then takes up in turn the field for standardization in steel specifications, inspection of materials, physical testing of steels, uniformity of composition of metals, heat-treating operations, methods of carburizing, depths of case-hardening, treatment after carburization, errors in overspeeding hardening operations and drawing heat-treatment at low temperatures. Types of pyrometers, operations on hardened work, inspection for hardness and selection of hardening equipment are some of the other topics discussed.

THE use of induction heat-treating, combined with precision quenching, particularly where only a portion of a product requires selective treatment, was one of the major applications of new processes which made possible the use of low-alloy steels and cast iron during the wartime shortage of high-quality materials, according to Mr. Somes. The application of the process to problems of the automotive industry is discussed by Mr. Somes, who suggests a number of products to which its use can be extended in the developments of the postwar period. The author also recounts the experiments which went on in the development of the process and its application to the selective heat-treatment, by induction heating, of the Ford passenger-car hub, to provide by bore hardening an integral bearing race. In the course of this presentation, he details the development of the process and its present applications both in the use of static and progressive cylinder heat-treat machines.

THIS paper includes the results of a study to determine how best to fabricate aircraft components made from precipitation-hardening aluminum alloys so as to take full advantage of the superior mechanical properties of these materials, and yet have parts that can be fabricated readily with a minimum of shop difficulties. The following characteristics of these alloys and problems incidental to their use are studied: mechanical properties, heat-treating operations, effects of cold work, problems connected with various forming operations, methods of attachment, machinability, finish requirements, means of inspection and identification of the various materials and their several tempers, and shop assembly procedures. The following shop fabrication procedures are recommended: 1. In cases where design dictates the use of precipitation-hardening aluminum alloys, the detail parts should be formed, whenever practicable, in the as-quenched solution heat-treated condition. 2.

This paper is a survey of the gear materials utilized in Automatic Transmissions by the major manufacturers of such transmissions. In conjunction with the material usage survey, consideration is given to the raw material form, heat treatment and final physical properties. The major problems of gear manufacture and some future developments in process methods are discussed. The paper brings out the fact that there is no uniformity in materials or methods used by all manufacturers, but each manufacturer has developed his own process, because of the particular design of transmission, the availability of equipment and materials or previous manufacturing processes.

PRESENTED here is an analysis of the gearing of 11 tractor transmissions. The material is discussed under the following divisions: 1. Basic gear systems in use. 2. Gear-form modifications and methods of final finishing. 3. Materials and heat-treatment. 4. Surface compressive stresses. 5. Beam stresses.

THIS paper presents the results of investigations conducted at the University of Michigan under the sponsorship of the International Nickel Co., Inc., to determine the influence of carbon, silicon, and phosphorus contents and of section size on the mechanical properties of ductile cast iron. Carbon contents in the range of 2.75% to 4.10% had a minor controlling influence on the mechanical properties. Silicon, through its influence on the matrix structure and its solid solution hardening effect, exerts a major effect on the mechanical properties. Increasing the silicon content from 0.1% to 5.0% produces linear increases in tensile and yield stregnths and hardness and decreases in ductility. Increasing the phosphorus content from 0.04 to 0.40% increases hardness and decreases ductility. Ductile iron exhibits moderate section sensitivity, either in the as-cast or fully annealed conditions. With increasing section thickness the properties are all lowered slightly.

THE design and application of tractor bevel gears is covered in this paper. The authors discuss the problems involved, under the following headings: 1. Basic bevel-gear systems in use, based upon the method of cutting. 2. Method of calculation and selection of factors determining the static and maximum tensile stresses. 3. Summary of static and maximum tensile stresses, and fatigue life analysis. 4. Materials and heat-treatment.