KR20130040790A - Self-lubricated coating and method - Google Patents

Abstract

The present invention relates to a method of providing a self-lubricating coating on a coating and a substrate. The method includes spraying one or more liquid metal layers onto a substrate using an inert gas; Adding a compound during spraying to the liquid metal sprayed on the substrate; Forming a porous layer on the substrate, the porous layer comprising the metal and the compound and having a plurality of pores; Heating the porous layer to open voids; Providing overflow of the grease material into the open pores such that a portion of the grease material is stored in the one or more pores; And cooling the porous layer to close the pores to trap the grease material inside the pores.

Description

Self-lubricating coatings and methods {SELF-LUBRICATED COATING AND METHOD}

Embodiments of the subject matter disclosed herein relate to methods and systems, and more particularly to mechanisms and techniques for providing self-lubricating coatings.

In the past few years, with the rising price of fossil fuels, interest in various aspects related to the processing of fossil fuels has increased. In addition, there is a growing interest in manufacturing more efficient and reliable motors, turbines, compressors and the like to facilitate good production and distribution of oil and gaseous products.

Such devices generally comprise a stationary part (stator) and a rotating part (rotor). The rotor is structured to rotate relative to the stator to achieve either the compression of the medium, the generation of electrical energy or the conversion of electrical energy into mechanical energy. The rotor needs to rotate with respect to the stator in a specific temperature range with minimal friction. Due to the continuous rotation of the rotor and its weight (which can be 20 to 20,000 kg and increase friction), a large amount of heat is generated. Heat is mainly generated in the bearings that support the rotor.

Thus, various mechanisms for cooling the bearing can be used. One such mechanism is to continuously circulate a medium, such as oil, between the rotor and the bearing, and remove excess heat by cooling the oil. The pump can be used to force oil circulation. However, if the pump fails, the oil stops flowing and, consequently, the removal of heat generated at the interface between the rotor and the bearing. In this environment, no oil may be present at the interface between the rotor and the bearing, which causes the bearing to increase in temperature to a point that will damage the rotor and / or the bearing or other parts of the device.

If the device stops because an abnormal condition is not quickly identified by the operator of the device or by a given system, the entire device is severely damaged resulting in the interruption of the entire process in which the device is involved, which incurs costs And undesirable in the gas industry. Even if a fault condition of a device is quickly identified, sometimes a failed device is not possible because many devices are correlated and it is not possible to quickly shut down one device without compromising the safety of the other devices. It may be impossible to stop immediately.

Thus, there is provided a system and method for providing a time buffer to the device operator between the moment when the device is unable to perform proper work and the moment when the device is damaged by high temperatures, such as when the oil pump fails. It would be desirable.

According to one exemplary embodiment, the present invention provides a method of providing a self-lubricating coating on a coating and a substrate. The method includes spraying one or more liquid metal layers onto a substrate using an inert gas; Adding a compound during spraying to the liquid metal sprayed on the substrate; Forming a porous layer on the substrate, the porous layer comprising the metal and the compound and having a plurality of pores; Heating the porous layer to open voids; Providing overflowing grease material into open pores such that a portion of the grease material is stored in one or more pores; And cooling the porous layer to close the pores to trap the grease material inside the pores.

According to another exemplary embodiment, a method for operating a turbo-device having a safety mechanism for a bearing is provided. The method includes rotating the rotor relative to the stator of the turbo-device; Supporting the rotor with a bearing comprising at least one porous layer, the at least one porous layer comprising a metal and a compound forming a plurality of pores, and a grease material stored in the pores; And providing lubricant to the bearing while rotating the rotor such that the operating temperature of the bearing is substantially constant.

According to another exemplary embodiment of the present invention, a stator having a fixed structure; A rotor configured to rotate relative to the stator; A bearing configured to support the rotor to facilitate rotation of the rotor; And a self-lubricating coating provided on the bearing or rotor. Said self-lubricating coating comprising at least one porous layer, said at least one porous layer comprising a metal and a compound forming a plurality of pores, and a grease material stored within said pores, said voids being of said bearing If the operating temperature is lower than the predetermined value, it is closed to capture the grease material.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments with descriptions describing these embodiments. The drawings are described below.
1 is a schematic diagram of a device having a rotor and a stator.
2 is a schematic diagram of a substrate having a self-lubricating coating in accordance with an exemplary embodiment.
3 is a diagram of a porous layer according to an exemplary embodiment.
4 is a flow diagram illustrating a method of providing a self-lubricating coating on a substrate, in accordance with an exemplary embodiment.
5 is a flowchart illustrating a method of operating a turbo-device with a safety mechanism, according to an exemplary embodiment.

The following description of exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings indicate the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed for the terminology and structure of the compressor for simplicity. However, the embodiments discussed in the following are not limited to the compressor and can be applied to other systems including a rotor supported on a bearing.

As used herein, the term “one embodiment” or “embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the subject matter of the disclosed invention. Thus, the phrases "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily referring to the same embodiment. In addition, certain features, structures, or features may be combined in any suitable manner in one or more embodiments.

According to an exemplary embodiment, the rotor, bearing, or part of both, stores the grease material while the device is operating at normal temperature and the grease when the temperature of the device is increased above a certain threshold temperature. It is coated with a self-lubricating coating with a structure that releases the material.

According to the exemplary embodiment shown in FIG. 1, the compressor 10 comprises a rotor 12, among others, of a structure that rotates with respect to the stator 14. The rotor 12 is for example supported by one or more bearings 16 at both ends. Various bearings are known in the art, and any such bearing is used to support the rotor 12. One example of a bearing is a journal bearing described in US Pat. No. 6,361,215, which is incorporated herein in its entirety.

The journal bearing 16 uses one or more pads 18 to support the rotor 12, and oil is injected into the interface 20 between the pads 18 and the rotor 12 to reduce friction and / or Cool the interface. A pump (not shown) may be used to pump oil through the channels 22 in each pad 18 at the interface 20 between the pads 18 and the rotor 12. If the oil ceases to be delivered to the interface 20, the temperature at this interface will increase beyond an acceptable value, which may damage the bearing 16, the rotor 12, or both.

According to the exemplary embodiment shown in FIG. 2, a portion of the rotor 12 or bearing 16 or both may be coated with a self-lubricating layer 24. Self-lubricating layer 24 may be deposited on substrate 26 as shown in FIG. 2, which may be one of rotor 12 and / or bearing 16. When the self-lubricating layer 24 is deposited on the rotor 12, it is desirable to deposit the bearing 16 directly opposite.

Layer 24 may include substrate material 28 that is deposited on substrate 26. The base material may include metals used in the bearing, such as gray cast iron, stainless steel, carbon steel or non-ferrous alloys, and the like. In one application, the base material is plastic, such as containing low content of carbon and high content of Fe, Ni or cobalt. In another application, the base material does not comprise Cr. In another application, the base material may comprise a non-ferrous metal such that the base material is plastic. The base material may be deposited by methods known in the art. For example, the base material may be sprayed onto the substrate. However, in one application, the base material layer 28 is not part of the layer 24. The base material layer 28 is deposited to ensure good adhesion between the self-lubricating layer 24 and the substrate 26.

Porous layer 30 providing a self-lubricating function is formed on substrate 26 or directly on substrate material layer 28. The porous layer 30 may include metals and compounds that facilitate the formation of voids in the porous layer 30. The metal may be one or more of a metal used in the bearing, such as gray cast iron, stainless steel, carbon steel, etc., depending on the use, hardness of the desired layer, load of the bearing. The compound may be one or more of graphite powder, molybdenum disulfide (MoS ₂ ), tungsten disulfide (WS ₂ ). The metal is sprayed as a liquid on the base material layer 28. For example, electric arc or plasma spraying can be used to spray the liquid metals and compounds. Inert gas under pressure can be used to deliver the molten metal from the gun or other device used to coat the substrate as well as to introduce the compound into the molten metal. For example, the inert gas can be nitrogen (N).

A porous layer 30 having a plurality of pores 32 distributed through the metal and compound mixture 34 is shown in FIG. 3. The number of the plurality of voids 32 depends on many variables. For example, the number of voids may depend on the temperature at which the liquid metal is sprayed on the substrate, the pressure of the inert gas, the distance between the gun and the substrate spraying the liquid metal, the specific metal used, the specific compound used, and the like. In one application, the thickness of the self-lubricating layer 30 is several μm to several mm.

When the porous layer 30 is formed on the substrate 26 and the temperature of the assembly drops to approximately room temperature (eg 25 ° C.), the voids are closed, for example when the porous layer 30 is immersed in the liquid bath, it is not meaningful. An insignificant amount of the liquid is introduced into the void layer 30. However, when layer 30 with substrate 26 is exposed (eg, immersed) to an oil bath at high temperatures, voids 32 in layer 30 open and oil begins to emerge from the voids. The high temperature range can be, for example, 80 to 500 ° C. depending on the oil type (synthetic or nonsynthetic, etc.). Although oil is used as an example, any grease material may be used to partially fill some or all of the voids in layer 30.

Substrate 26 and layer 30 are then cooled to room temperature to seal the voids so that the absorbed grease material is stored inside voids 32. This substrate with self-lubricating layer 30 is then used in one or more of the devices described above. Thus, when such a device ceases to provide oil to the interface between the rotor and the bearing, the temperature at the interface increases beyond the temperature that opens the pores of the self-lubricating layer 30, which causes the porous layer 30 to become a rotor. Determine to release the grease material at the interface between the and bearing.

Depending on the size and distribution on the bearings and / or rotors, this self-lubricating layer 30 provides several minutes (if not hours) of safe operation to the device operator despite the failure of the main oil supply mechanism of the device. Can be provided. In this way, the operator has the time required to shut down the entire processing line in a controlled manner without compromising the safety of the other devices making up the process line.

While it may be intuitive to provide a thick self-lubricating layer 30 to provide longer grease material, it has been found that the thicker layers are more prone to cracks and have a shorter lifespan. In addition, cracks in the thick layer can cause the grease material to be released earlier than desired, and can also impair the adhesion of the porous layer to the substrate. In contrast, thin layers are undesirable because insufficient grease material may be stored. Accordingly, the appropriate thickness of the self-lubricating layer 30 depends on the type of device, the weight of the rotor, the number of pads and the number of bearings, and the like.

According to the exemplary embodiment illustrated in FIG. 4, a method of providing a self-lubricating coating on a substrate is provided. The method includes spraying (400) one or more liquid metal layers onto a substrate using a gas; Adding (402) a compound during spraying to the liquid metal sprayed onto the substrate; Forming (404) a porous layer on the substrate, the porous layer comprising the metal and the compound and having a plurality of pores; Heating the porous layer to open a void (406); Overflowing the grease material into the open pores such that a portion of the grease material is stored in one or more pores; And cooling the porous layer to close the pores to trap the grease material inside the pores (410).

However, when depositing a ferrous layer, N ₂ gas may be used because N ₂ gas is cheaper. In addition, N ₂ gas can provide more plasticity to the porous layer, which is desirable. N ₂ gas is superior to argon or compressed air because it prevents oxidation of alloying elements in the liquid metal and does not alter the composition of the deposited layer.

According to the exemplary embodiment shown in FIG. 5, a method of operating a turbo-device with a safety mechanism for a bearing is provided. The method includes rotating (500) a rotor relative to the stator of the turbo-device; Supporting the rotor with a bearing comprising at least one porous layer, wherein the at least one porous layer comprises a metal and a compound forming a plurality of pores, and a grease material stored in the pores; And providing 504 a lubricant to the bearing while rotating the rotor such that the operating temperature of the bearing is substantially constant.

The disclosed exemplary embodiments provide a system and method for providing grease material when the provided grease material supply fails. It should be understood that the above description is not intended to limit the invention. To the contrary, exemplary embodiments are intended to include alternatives, modifications and equivalents, which are included within the spirit and scope of the invention as defined by the appended claims. In addition, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a broad understanding of the claimed subject matter. However, it will be understood by those skilled in the art that various embodiments may be practiced without these specific details.

Although features and elements of the present exemplary embodiments have been described in the embodiments in particular combinations, each feature or element may be used alone or without or with other features and elements disclosed herein. It can be used in various combinations.

The description herein utilizes examples of the disclosed subject matter, including the manufacture and use of any device or system, and any methods included, to enable one skilled in the art to practice the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be included within the scope of the claims.

Claims (10)

Spraying at least one liquid metal layer onto the substrate using a gas;
Adding a compound during spraying to the liquid metal sprayed on the substrate;
Forming a porous layer on the substrate, the porous layer comprising the metal and the compound and having a plurality of pores;
Heating the porous layer to open voids;
Flooding the openings with grease material such that a portion of the grease material is stored in one or more pores; And
Cooling the porous layer to close the pores to trap the grease material within the pores
A method of providing a self-lubricated coating on a substrate comprising a. The method of claim 1,
The liquid metal is one of the metals used in bearings, gray cast iron, stainless steel, carbon steel or non-ferrous alloys. 3. The method according to claim 1 or 2,
Wherein the compound is one of graphite powder, molybdenum disulfide (MoS ₂ ), tungsten sulfide (WS ₂ ), or a combination thereof. The method according to any one of claims 1 to 3,
A base material comprising a low content of carbon and a high content of Fe, Ni or cobalt, or a plastic non-ferrous metal is provided on the substrate prior to the spraying so that a porous layer is formed on the substrate material. Formed to allow for better adhesion on the substrate
≪ / RTI > The method according to any one of claims 1 to 4,
Wherein the heating is accomplished by immersing the porous material into the grease material at a predetermined temperature. 6. The method according to any one of claims 1 to 5,
Wherein the substrate is a bearing of a compressor. 7. The method according to any one of claims 1 to 6,
And the gas comprises nitrogen (N). Method of operation of a turbo-device having a safety mechanism for a bearing,
Rotating the shaft relative to the stator of the turbo-device;
Supporting the shaft with a bearing comprising at least one porous layer, the at least one porous layer comprising a metal and a compound forming a plurality of pores, and a grease material stored in the pores; And
Lubricating the bearing while rotating the shaft such that the operating temperature of the bearing is substantially constant
/ RTI > The method of claim 8,
Stopping the provision of the lubricant;
Increasing the operating temperature of the bearing; And
Opening the voids in the one or more porous layers to allow the stored grease material to exit the voids to lubricate the bearing.
≪ / RTI > A stator having a fixed structure;
A shaft configured to rotate relative to the stator;
A bearing configured to support the shaft to facilitate rotation of the shaft; And
Self-lubricating coating provided on the bearing or shaft
As a turbo-device comprising:
The self-lubricating coating comprises one or more porous layers,
The at least one porous layer comprises a metal and a compound forming a plurality of pores, and a grease material stored within the pores,
The void is closed when the operating temperature of the bearing is lower than a predetermined value to capture the grease material.

Images