DE1912253A1 - Element coming into contact with gas with leading and trailing edges - Google Patents

Description

Dr. Ing. E. BERKENFELD · Dipl.-Ing. H. BERKENFELD, patent attorneys, Cologne Attachment file number

to ^ ingabevof March 12, 19Ö9 Sch // Name d. Note UNITED AIRCRAFT CORPORATION

Element coming into contact with gas with leading edge and trailing edge attachment.

The invention relates to an element coming into contact with gas, the leading edge and trailing edge of which have an exceptionally high temperature resistance and exceptional corrosion resistance Have erosion properties.

It was recognized a long time ago that the use of connections made of metal and refractory material offer particular advantages as building materials for high temperature applications. These composite components are used and have clear advantages, especially when operating gas turbines or similar. In a gas turbine, the elements of the machine that come into contact with the gas are continuously one exposed to very harsh and complex environments, such as high temperatures, large temperature gradients, erosion as well Forces which tend to deform the elements coming into contact with the gas. These forces have a particularly damaging one Effect on the front and rear edges of the elements in contact with the gas. As a result of the large temperature gradients and other thermal conditions presently encountered in gas turbines in contact with the gas encounter upcoming elements are the permissible operating periods and operating temperatures of these elements in contact with the gas are considerably limited.

Composite components are known and the one in the American Compound described in U.S. Patent 3,215,511 Component is a typical example of such components. The well-known 6/132 909840/1113 _- ,.

th composite components generally use a ceramic or another similar material in combination with a high temperature alloy. The composition of the component .is such that the high-temperature alloy compared to the ceramic or other material forms the predominant component. Although this component is an improvement over the Generally used metal components represents, the same is by no means the ideal solution, because the permissible operating periods and operating temperatures of the component are still limited are, the metal alloy and its properties forming the regulating factor.

Composite components are also known which are applied and used in the field of construction, for example for prestressed concrete. Although there is a certain JÖiliehkeit between these components and the present invention, these known components can neither be used for high temperature applications, nor do they have the properties which result in high temperature stability and resistance to oxidation, sulfidation and erosion, especially on the leading and trailing edges of a with Gas element coming into contact.

The object of the invention is to develop an element that comes into contact with gas, which has high creep resistance is resistant to oxidation, sulphidation and erosion and has favorable shock load properties at low temperatures having.

The component according to the invention has a central main part made of a high temperature alloy and one with the central one Main part connected leading edge approach. This consists of a refractory material, preferably a ceramic material, and from a large number of metal cores, preferably made of an alloy based on nickel or cobalt. In addition, on middle main part a trailing edge attachment with essentially the same construction to be attached, creating one with gas contacting element is obtained which has improved properties in its most vulnerable places.

u 6/152 909840/1113 ~ ² ~

The process of making the leading and trailing edge approaches according to the invention is described in American patent application no. 7.1 ^ 736 dated March 20, 1968. Accordingly points the refractory or ceramic material exhibits a different rate of thermal contraction than the single crystal metal wheels. As a result, as the melt cools, the refractory material is prestressed to compression. With the component According to the invention, the main task of the metal cores is to distribute the load and protect the refractory material from one catastrophic failure in the event of a thermal shock or a shock load at low temperatures, while the main task of the Refractory or ceramic material is made for creep resistance and to provide resistance to oxidation, sulphidation and erosion.

According to another feature of the invention, there is no bond between the metal and the refractory mass. The refractory Mass is held in place either by the outside extended ends of the metal veins or by the columnar structure, which at the top and bottom of the leading and trailing edge approaches is maintained upon removal of the element in contact with the gas from the mold. This the latter section of the element in contact with the gas, i.e. the columnar structure at the lower and upper end of the front and rear edge attachments also has the secondary effect, that it maintains the useful compressive stress developed in the refractory mass.

The arrangement and number of longitudinal holes in the fires Solid masses are also important in the leading and trailing edge approaches. In certain cases it is desirable to have an uneven distribution of the single crystal metal veins within the refractory so that the correct number of veins is obtained for any desired pressure distribution and pressure height. Near the outside is a uniform high level of compressive stress is required to initiate cracking and growth in the refractory delay. The metal veins should therefore be very thin and small Distance from each other. The size of the veins and the

^u 6/132 909840/11 13 -3-

However, restrictions are imposed on distance between them both by casting the metal and by the molding processes the refractory mass. The main limitation of the construction of this type is that the component must be designed so that no bending moments occur. This can be taken into account are maintained by maintaining a relatively constant volume fraction of the metal from the leading edge to the trailing edge will. There are also applications of the present invention in which it is desirable to have an even distribution of the To have single crystal metal veins within the ceramic material. In another configuration, the element that comes into contact with the gas, or the leading and trailing edge projections, has same on a plurality of passages for cooling air, which are arranged within the refractory mass. This training has significant advantages in that the level of compressive stress in the refractory mass is proportionate even at operating temperatures is great. Stress relief within the single crystal metal veins occurs at much slower speeds occur due to the higher stability at lower metal temperatures.

For a better understanding of the invention, reference is made to the drawing taken, in which shows:

Fig. 1 in longitudinal section a preferred mold construction for Manufacture of the component according to the invention,

Fig. 2 schematically in cross section along the line 2-2 of Fig. 1 with the front and rear edge approach of the component evenly distributed single crystal metal veins.

In Fig. 1, a preferred embodiment of the mold is shown. The mold construction described below is particularly suitable for the so-called superalloys, which are described, for example, in American patent specification Z> 260 505. These alloys are generally suitable for the process known as directional solidification, with the most preferred alloy being a nickel or cobalt based alloy. Used in addition to the disclosure in this specification; ^{u 6/1} 32 909840/1113 - ^ - \

the mold construction described below uses the technique of formation of Single Crystal Alloys ™ described in U.S. Patent Application No. 540 114 filed February 17, 1966.

One end of a tubular shape 4 intended for use at that described in US Pat. No. 3,260,505 The method is suitable is arranged on a relatively cool, thermally conductive and preferably water-cooled plate 6. The tubular form 4 is preferably made of a ceramic material consisting of a conventional slurry of alumina or another refractory material with a high melting point according to the normal shell molding technique. The water for the cooling plate 6 is supplied through the lines 8. One end of the tube 4 rests on the cooling plate 6 and cooperates with it to form an enclosed cavity. A passage 12 communicates with the cavity 10, through which the cavity 10 is supplied with molten metal. . .

The cavity 10 is surrounded by the means for heating the mold to the temperature desired for casting. The cavity is preferably surrounded by an electrical resistance heating winding 14 which is fed with a variable electrical current. The cavity can, however, also be surrounded by a graphite susceptor (not shown), which in turn is surrounded by an induction resistor that is fed with high-frequency electrical current, as is the case with an induction furnace. Before casting, the mold is heated to a desired temperature by applying current to the winding 14. When the desired temperature is reached , molten metal, heated to the temperature required for casting, is poured into the cavity. The cooling plate ¹ 6 is maintained at a relatively never drigen temperature by water is set by the lines 8 in circulation in order to erseugen a temperature gradient within the filled cavity with the molten metal 10 since separated solidified "metal."

iel 4 "r 4 * re" * fc "Uten Au" rührun "3forra is a" shaped refractory mold 16 inserted into the cavity 10, although only one

^{u 6/1 * 3 9 0 9} 8 4 0/1113 -5-

Shaped shape is shown, a plurality of shapes can of course be used at the same time. The molded shape 16 of the invention has a leading edge extension 18 and a trailing edge extension 20 of a stator vane connected to a main central portion 22 at 22 and 25, respectively. This training is shown more clearly in FIG. For the present description, the leading edge extension 18 and the trailing edge extension 20 have essentially the same training. The main part 24 of the leading edge extension 18 consists of a refractory mass with a relatively low tensile strength, which is about 0.70-70.3 kg / cm. The casting of the single crystal veins in the refractory mass enables the mass to be used with this relatively low tensile strength. In some applications, however, a composition having a high tensile strength may be desired and used for the invention described below. The refractory mass 24 has excellent heat resistance properties and can withstand temperatures up to about 1900 ^° C. An ideal refractory has been found to be an alumina-based ceramic material. The refractory mass 24 of the leading and trailing edge extensions 18 and 20 has a plurality of bores 26. These bores 26 are longitudinal bores, ie they extend from the lower end 30 upwards to the upper end

32 of the leading and trailing edge approaches. In order to promote the growth of individual crystals within these longitudinal bores, the same can have a constriction or a relatively small opening at the lower end. Thus, after molten metal has been poured into cavity 10 and begins to solidify, it has a regulated columnar structure. By arranging a small opening 36 or a constriction (not shown), the growth of individual crystals within the longitudinal bores 26 is promoted. The single crystal veins

33 (Fig. 2), which grow inside the longitudinal bores 26, can be inserted in the same direction on the upper edge 32 of the front and rear edges * naneätx · xueanunenwacha «n and the columnar grain structure llt as dl · glulenfCraig · grain structure at the lower end 30 of the front and rear edges. In other words, the lower end 30 has the tubular grain structure like the upper band 32, that is, by means of a central Abu 6/132 909840/1113 ~ ⁶ ~

BATH

cut of the single crystal veins jj8 are separated.

Once the novel casting method described above has been used to enable the growth of a columnar structure at the lower end J> 0 along with a central portion of the single crystal veins J> Q and an upper end j52 having substantially the same columnar structure as the lower end , the melt is allowed to cool. As a result of this cooling, the ceramic or refractory mass 24 becomes compressive due to a difference in the rates of thermal contraction of the two materials. In other words, the ceramic part 24 is preloaded in compression due to the greater thermal contraction of the single crystal metal veins 38. This compressive stress developed in the ceramic part 24 is extremely useful, know. it eliminates crack nucleation, causes cracks to close at elevated temperatures, and impairs crack propagation.

The single crystal veins 38 can be within the refractory mass 24 be evenly or unevenly distributed, which can be attributed to the arrangement of the longitudinal bores 26 within the refractory mass is dependent. Like Pig. 2! Shows, the leading edge approach has a relatively even distribution of the veins within the refractory mass, while the trailing edge approach is uneven Shows distribution of veins within the refractory mass.

In some embodiments, it may be desirable for the refractory mass .24 to be provided with a plurality of coolant passages is. These passages result according to the invention in that in one of the. Longitudinal bores 26a no growth is promoted, so that they remain free for the passage of cooling air.

In the preferred embodiment of the invention it is highly desirable that the refractory mass be the continuous portion which forms leading or trailing edges. In particular in the illustrated embodiment, the refractory mass be continuous or form a one-piece element of clay of the leading and trailing edge extensions.

909840/1113

ORIGINAL INSPECTED

preferred leading or trailing edge approaches are illustrated by the following example.

example

A composite component in which the refractory mass consists of 99% alumina (McDanel AP J55 from McDanel Refractory Porcelain Co., Beaver Palls, Penns.) And the single crystal veins, which pass through longitudinal bores within the mass, are made from the superalloy Mar-M -200 nickel base consist (wt -.% C 0.15, 9 Cr, 10Co, 2 Ti, 5 Al, 12.5 W, 1.0 Nb, 0.05 Zr, 0.015 B, 1.5 Pe, residual Ni). Longitudinal bores with a diameter of 0.76 mm are in a hexagonal arrangement within ^ the refractory mass at a small distance from one another. With a center-to-center distance of the holes of 1.55 mm, the refractory mass contains 30 volume ^ single crystal veins after casting. The voltage in the refractory mass or in the metal wires is:

^E 2 ^V 2

and

Λ «= ~ - TZ 4oZ Δ Τ (2)

V _{1 +} E ₂

where means:

HI average Young modulus of alumina E ₂ """" Mar-M-200

V _{1 part by} volume of clay

V ₂ "of the cores made of Mar-M-200

- 1 2

⁰ ^ ^ average coefficient of linear thermal expansion of

-7- clay

⁰ ^ ₂ """from Mar-M-200

~ 4 T operating temperature-ambient temperature U 6/132 ". -8-

909840/1113

It is assumed that the stress in the ceramic material and in the metal wheels is zero at the operating temperature.

We, nn use the following values:

kJ = 3.52. 10 ⁶ kg / cm ²

E ₂ = 1.12. 10 ⁶ kg / cm ²

V ₁ = 70 volume #

V ₂ = 30 volume #

^ ₁ = 7.8. io " ⁶ / ° c

i7 _o = 13.1. 10 " ⁶ / ° C and

-ΔΤ = 1000

C.

are the calculated voltages in the ceramic material or in the metal wires:

tf ^ = 2278 kg / cm ² (1)

^ = 5186 kg / cm ² (2)

Claims

U 6/132 -9-

909840/1113

Claims (8)

Dr. Ing. E. BERKENFELD · Dipl.-Ing. H. BERKENFELD, Potentanwälte, Cologne System . File number for inspection from March 12, 1969 Sch // Name d. Note UNITED AIRCRAFT CORPORATION Claims Element that comes into contact with gas, labeled h a main part and a leading edge extension which is connected to the main part and which has a lower end with a unilateral Has set structure, a middle section with a plurality of single crystal wheels and an upper one End, which has essentially the same structure as the lower end, and by a refractory mass with a A plurality of longitudinal bores is provided and which is arranged between the upper and lower ends, the single crystal wheels pass through the longitudinal bores within the mass and the refractory mass has a lower speed of thermal contraction as the lower end, the middle section and the upper end, so that the refractory mass this is preloaded to compression. 2. Coming into contact with gas element according to claim 1, characterized by a trailing edge approach with the Main part is connected and which has essentially the same design as the leading edge approach. 3. Gas-contacting element according to claim 1 or 2, characterized in that the holes in the fire-resistant mass of the leading edge approach and the trailing edge approach are evenly distributed in the mass. 4. Gas contact element according to claim 1 or 2, characterized in that the holes in the refractory Dimensions of the leading edge approach and the trailing edge U 6/132 909840/1113 -10- sentence are unevenly distributed in the "mass. 5. With gas coming into contact element according to any one of claims 1-4, characterized in that the central portion the main part consists of a single crystal of a high temperature alloy, the base of which is selected from the group, which contains nickel and cobalt. 6. Gas-contacting element according to claim 1, which consists of a stator blade that comes into contact with gas which is used in a gas turbine, characterized in that the leading edge approach with the upstream arranged edge of the main part is connected and that the Refractory mass is a continuous mass relative to the single crystal veins. 7. Gas contact element according to claim 2, which consists of a stator blade that comes into contact with gas which is used in a gas turbine, characterized in that the trailing edge approach with the downstream arranged edge of the main part is connected. 8. Coming into contact with gas element according to any one of the preceding claims, characterized by a plurality of Coolant passages within the refractory mass. U .6 / 132 .. -11- 909 8 40/1113 Blank page