FR2546448A1 - COATED METALLIC OBJECT AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

THE INVENTION RELATES TO A COATED METAL OBJECT AND TO A PROCESS FOR ITS MANUFACTURING. THE PROBLEM TO BE SOLVED IS TO OBTAIN HIGH HARDNESS AND COMPRESSION RESISTANCE AS WELL AS A REMARKABLE WEAR RESISTANCE WITHOUT THE CHOICE OF THE BASE MATERIAL IS A CRITICAL POINT. THE OBJECT IS CHARACTERIZED IN THAT IT CARRIES ON ITS SURFACE A COATING IN THE FORM OF A TABLECLOTH ON WHICH A LAYER OF MATERIAL OF HIGH MECHANICAL RESISTANCE IS DEPOSITED. THE INVENTION IS APPLICABLE IN PARTICULAR TO PARTS SUBJECT TO WEAR, SUCH AS HOLDERS, TAPPETS AND CYLINDERS.

Description

"Coated metallic article and process for its manufacture"

  The invention relates to an object to which, by a coating

  special treatment, both hardness and resistance to

  pressure, that a remarkable wear resistance.

  The invention extends to a method for the manufacture of such a coated object. It is known to melt the surface of steel parts by adding at the same time alloying elements, so that after solidification it is communicated to the surface of the piece

  thus treated desired specific properties.

  Thus, steel surfaces have already been laser irradiated, the diffusion of added alloying elements taking place in the locally melted surface (this is the process called

  "laser alloy") By combining chrome and carbon at the same time

  bone, hard surfaces are made with deposits of Cr 3 Cr 2 aya

  a uniform particle size and morphology.

  However, such a pretreatment of the metal surfaces is naturally subject to considerable limitations. The addition of determined surface alloying elements, which leads to good surface properties for a given steel, may, for another steel, lead to to obvious failures because of its different basic composition, and this is because, as a result of the melting of the surface part, components of the base alloy are taken up in the surface alloy. results obtained during the surface treatment of a particular steel are not transportable to the treatment of another steel, such a transposition is even less possible to other metals and to

other metal alloys.

  Another disadvantage arises when, in order to increase

  In order to achieve the compressive loading capacity, it is attempted to ensure that a component treated according to the above method is additionally provided by applying the chemical vapor deposition process or the physical deposition method in phase. vapor, a wear resistant layer in terms of high mechanical strength such as, for example, Ti C or Ti N.

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  Indeed, in this coating process, the temperatures at

  to use are so high that, under their action, resistance to compres-

  the resultant treatment of the surface piece disappears as a result of the microstructure modifications of the base material if not well-defined base materials resistant to microstructure variations are used. such

  only with a very limited choice.

  Therefore, the purpose of the invention is to create a

  coated metal object which, as a result of its coating,

  both with a hardness and a solicitation capacity

  particular compression strengths

  the choice of basic material is not a critical

  It is another object of the invention to provide a method for

  the manufacture of such a coated object.

  For this purpose, the subject of the invention is an object of the type

  above characterized in that it bears on its surface a coating-

  in the form of a sheet on which there is a layer of

of high mechanical strength.

  The process for making such a metal object

  characterized in that a web-like coating is applied to the surface of a base material and a layer of high-strength material is then deposited on the coating.

tablecloth shape.

  Thanks to the invention, a highly wear-resistant object is obtained from a metal base body, with a hot-isostatically compressed high-strength hard-material coating and a surface coating of the same. material

high mechanical coating.

  The principle of construction of the object is essential-

  next; a ductile and tenacious base material,

  inexpensive, is provided by means of a suitable technique, a coating of high strength in the form of a sheet whose thickness can range from a few tenths of a millimeter to a few millimeters Then, after a superficial machining (very

  light) of surfaces subjected to wear during operation, it is

  reads the chemical process of vapor deposition (CVD process) or

2 _ 5 4 '' 6 4 '4' 8,

  or the physical vapor deposition process (PVD process) for depositing a surface layer on the sheet-like coating

extremely hard thin.

  Appropriate techniques for the application of the

  cloth-shaped garments are: projection (plasma, flame), tungsten welding under inert gas (WIG process) or laser, and in particular hot isostatic pressing (HIP process). isostatic hot compression is the formation of a fine-grained isotropic microstructure for the chosen coating material and in the weak

  importance of the mechanical machining of the surface that must be

  after the fact For the formation of the coating in the form of napl

  all powdered materials that provide mechanical strength

  at least 2000 N / mm 2 are suitable. These include, for example, cold machining steels, high-speed steels, stellites and

hard metals.

  Suitable materials for the following surface coating are all hard materials that can be deposited using the CVD (Chemical Vapor Deposition) process and the PVD (Physical Vapor Deposition) process, preferably for CVD process: titanium nitride (Ti N), titanium carbide (Ti C), chromium carbide (Cr Cx), aluminum oxide (A 1203) and combinations of these products (this is ie multiple layers) and, for the

  PVD process: titanium nitride (Ti N).

  The construction elements to be coated or covered can, as is generally customary, be manufactured at a lower dimension

  the theoretical rating to take into account the thickness of the coating and the coating

vrement.

  The invention will be better understood with reference to the description

  with reference to the following description relating to realizations

  Example 1: Until now, the pump shafts have been made entirely of hard metal to resist wear. This solution is expensive and, because of the fragility

  hard metal, it can lead to breaks.

  In accordance with the invention, a GX 22 Cr Ni 17 steel shaft sheath was then produced as a base material to meet corrosive environment conditions.

  manufacture taking place at a rating lower than the theo-

  On the steel base, a hard metal coating was welded by diffusion with a nickel binder to the operating surface according to the HIP process for three hours at 1200 OC and 1000 bar. The coating thickness was

  approximately 2 mm and led to a dimension exceeding

  the mechanical dimension, the surface of the coating was brought to a value of 1/100 mm less than this theoretical dimension. On the polished surface, the CVD process was first deposited at 1050 ° C. and two hours one-layer of Ti C thick 3 to 5 y and then, in two hours and at a temperature conorized between 9500 C and 10000 C, a layer of Ti N about 5 yd thick The deposit was made in using titanium (IV) gilding and nitrogen in

  hydrogen as a carrier gas.

  Alternatively, the metal coating has been applied

hard by plasma projection.

  The shaft sleeves according to the invention have

  could have been manufactured much more economically than until now

  The wear resistance was as good as with a

  completely made of hard metal But the security of

  nipulation has been significantly improved compared to this

last achievement.

Example 2

  On a C 45 steel valve pusher plate

  made with a rating lower than the theoretical rating, it was

  by diffusion using the HIP process, for 3 hours at 1050 ° C. at 1000 bar, a coating 1 mm thick made of a carbon-rich cold work steel containing 2.3% C 13% Cr, 4% V and 1% Mo The coating was polished Next, the pusher was coated with Ti C by the CVD method, the Ti C having been deposited from Ti C 14 and methane (CH 4) in H 2 as

  gaseous vehicle The coating was carried out at 1050 OC.

  The coating time was two hours and a coating thickness of about 1 was obtained. The cold-worked steel was tempered by gas cooling from the temperature.

  This steel has subsequently undergone

nuation of internal tensions.

  Alternatively, the cold-work steel coating was applied by WIG welding. The pusher thus manufactured was distinguished by a very low coefficient of friction and resistance to

high wear.

Example 3

  On a hot rolled steel stamping pad x 40 Cr Mo V 5 1, a stellite coating having a composition of 1.05 to 1.25% C was applied by diffusion bonding, 27 to 30% Cr, 4 to 5% W, 1 to 1.25% Si and the remainder in Co, the application having been carried out according to the method HIP for three hours The conditions of application were the following.

  : 1,100 OC and 900 bar After the mechanical finishing work

  nique, it was deposited on the stellite coating, following the

  CVD, a layer of A 1203 with an intermediate layer of

  Ti N Ti N was deposited as in Example 1 for one hour.

  The temperature was then raised to 10,000 ° C and A 1203 was deposited with Al C 13 and C 02 in hydrogen as a carrier gas. the filing time was also one hour; A layer of A 1203 of about 5 Å was then produced. The matrix filling was then quenched.

  under vacuum and to income treatment.

Example 4

  A 12% chromium refractory steel impeller blade was, similarly to Example 3, provided on its flow edge with a stellite coating by the HIP process, and coated with TiN and A 1203 using the CVD method Dawn

  The turbine was then subjected to a separate heat treatment.

Example 5

  On a S 6-5-2 high speed steel spinning cylinder, diffusion welding was applied at 1200 OC and under 1000

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  bars, according to the HIP process, a 2 mm thick cobalt-bonded hard rubber coating, the duration of the operation was three

  hours After the rectification and polishing of the

  clothing, the cylinder was coated with 5 yd Ti N using the

  PVD according to the "ion plating" variant (ionic coating).

  Titanium was then vaporized by means of an electron beam and reacted with nitrogen. It was worked with a substrate bias voltage of 1 kV and a gas pressure of about 10-3 mbar. substrate temperature was equal

at 500 C.

  With the spinning machine according to the invention, a considerable improvement in the operating time has been achieved.

  compared to the high speed steel cylinders usually used.

Example 6

  Mixing and transport screws as well as

  hot-rolled steel anti-return glands (X 40 Cr Mb V 5 1), as used in plastic machines, the HIP process was equipped with a 0.5 mm coating high-speed steel thickness having the composition: 1.3% C, 4.2% Cr, 6% W approximately,

  4 to 5% Mo, 3 to 4% V and the remainder Fe, at 1050 C and under 1000 bar.

  The diffusion time was three hours After the mechanical finishing treatment of the operating surfaces, the elements were coated with Ti C according to the CVD method, as in the example

2, but for four hours.

  A layer of Ti C having a thickness of 6 to 8 y was obtained after the CVD treatment, the elements were subjected to

  vacuum quenching at 1060 ° C. and were tempered at 54 ° C.

7.

Claims (3)

CLAIMS 2546448   1) coated metal object, characterized in that it carries on its surface a coating in the form of a sheet on which   a layer of high strength material is deposited.   20) Object according to claim 1, characterized in that it consists of a ductile and tenacious base material,   a web-like coating formed from a pulverulent material   vortex and a layer of high strength material deposited on him.   30) Object according to any one of claims 1 and   2, characterized in that the pulverulent material is a steel for   cold work, high speed steel, stellite and / or hard metal.   Object according to any of the preceding claims   cedentes, characterized in that the layer of resistance material   high mechanical strength is Ti N, Ti C, Cr Cx, A 1203 or combinations of these materials.   Object according to any one of claims 1 to 4,   characterized in that the basic material is a steel of the classes   No. 10 to 80 (special unalloyed and alloyed steels) according to the   number of material numbers (steel-iron list, 7th edition 1981, page 5).   6) Process for producing a coated metal object according to   any of claims 1 to 6, characterized in that   applies a sheet-like coating to the surface of a   base and then deposit a layer of resistance material.   high on this web-like coating.   Process according to claim 6, characterized in that   that a strong and tenacious base material is   Plasma-sputter-type clothing by flame, WIG (tungsten inert gas) or laser   Hot isostatic compression (HIP).   8) Process according to any one of claims 6   and 7, characterized in that the layer of resist material is deposited   high mechanical strength according to the CVD process (chemical deposition   vapor phase) or the PVD (Physical Vapor Deposition) process.