A stellite coating and method of making same

Abstract

This invention provides a Stellite alloy coating and its preparation method, relating to the field of surface engineering. The preparation method includes: preheating and holding: placing the original Stellite alloy coating and its substrate in a vacuum furnace for preheating to 100–300°C and holding at that temperature, with the coating thickness to substrate thickness ratio being the thickness ratio, and the holding time being positively correlated with the thickness ratio; semi-remelting and solidification: using a temperature 20%–35% of the melting point of the Stellite alloy as the remelting temperature, remelting the coating surface and waiting for the melt to solidify; after the first pass of semi-remelting and solidification is completed and the coating cools to 100–300°C, N more passes of semi-remelting and solidification are performed, where N is a natural number, 0 ≤ N ≤ 5; cooling: after all passes of semi-remelting and solidification are completed, the coating is cooled to room temperature to obtain the Stellite alloy coating. This preparation method results in finer grains in the Stellite alloy coating, better adhesion to the substrate, reduced weight loss by more than half under abrasion, and significantly improved abrasion resistance.

Description

Technical Field

[0001] This invention relates to the technical field of surface engineering, and more specifically, to a Stellite alloy coating and its preparation method. Background Technology

[0002] High-temperature corrosion and high-temperature wear are both major causes of material damage. Commonly used wear-resistant coatings, such as Stellite alloy coatings, have excellent wear and corrosion resistance. Due to their superior performance, the application range of Stellite alloy coatings is expanding, covering fields such as aerospace, mechanical valves, medical devices, wood cutting, gas turbines, military and defense, and additive manufacturing.

[0003] Stellite alloys are relatively inexpensive, so it is of great significance to further improve the wear and corrosion resistance of Stellite alloy coatings to expand their application range and replace certain expensive materials. Summary of the Invention

[0004] The first objective of this invention is to provide a method for preparing Stellite alloy coatings, thereby addressing the technical problem that the wear and corrosion resistance of Stellite alloy coatings in the prior art needs to be further improved.

[0005] The Stellite alloy coating preparation method provided by this invention includes the following steps:

[0006] Preheating and heat preservation: The original Stellite alloy coating and its substrate are placed in a vacuum furnace and preheated to 100-300°C and kept at that temperature. The ratio of coating thickness to substrate thickness is called the thickness ratio, and the heat preservation time is positively correlated with the thickness ratio.

[0007] Semi-remelting and solidification: The remelting temperature is set at 20% to 35% of the melting point of Stellite alloy. The coating surface is then remelted and allowed to solidify.

[0008] After the first pass of semi-remelting and solidification is completed and the coating has cooled to 100-300°C, N passes of semi-remelting and solidification are performed again according to the above steps, where N is a natural number and 0≤N≤5.

[0009] Cooling: After all passes of semi-remelting and solidification are completed, the coating is cooled to room temperature to obtain the Stellite alloy coating.

[0010] Furthermore, the range of N is: 2≤N≤5.

[0011] Furthermore, if K≤1 / 5, the heat preservation time is 30-60 minutes;

[0012] If 1 / 5 < K < 1 / 2, the heat preservation time is 90 to 150 minutes, preferably 120 minutes;

[0013] If 1 / 2≤K≤1, then the heat preservation time is 180~210min, preferably 200min;

[0014] If K > 1, the heat preservation time is 240-300 min, preferably 250 min; where K is the thickness ratio.

[0015] Furthermore, during the preheating and heat preservation process, the heating rate of the original Stellite alloy coating and its substrate is controlled to be no higher than 100℃ / h.

[0016] Furthermore, during the preheating and heat preservation processes, a protective gas is introduced into the vacuum furnace, and the flow rate of the protective gas is controlled to be 0.5–5 ml / min.

[0017] Furthermore, during both the semi-remelting and solidification processes, a protective gas is blown onto the molten surface, and the flow rate of the protective gas is controlled to be no less than 15 ml / min.

[0018] Furthermore, during the semi-remelting process, the coating is subjected to laser remelting or induction heating remelting.

[0019] Furthermore, before preheating, the surface of the original Stellite alloy coating is cleaned until the surface roughness Ra is not higher than 100.

[0020] Furthermore, during cleaning, acetone is used to clean the surface of the original Stellite alloy coating.

[0021] The Stellite alloy coating preparation method provided by this invention can produce the following beneficial effects:

[0022] The Stellite alloy coating preparation method provided by this invention remelts the existing Stellite alloy coating at a temperature lower than the melting point of Stellite alloy, making the grains of the Stellite alloy coating finer and the bonding with the substrate better. Under the action of abrasion, its weight loss is reduced by more than half. Therefore, the Stellite alloy coating preparation method provided by this invention can significantly improve the abrasion resistance of Stellite alloy coating, which is of great significance for the full application of Stellite alloy.

[0023] The second objective of this invention is to provide a Stellite alloy coating to address the technical problem that the wear and corrosion resistance of existing Stellite alloy coatings needs to be further improved.

[0024] The Stellite alloy coating provided by this invention is prepared by the above-described Stellite alloy coating preparation method. Compared with existing Stellite alloy coatings, the Stellite alloy coating provided by this invention has finer grains and better adhesion to the substrate. Under abrasion, the weight loss is reduced by more than half, and the abrasion resistance is significantly improved, making it suitable for wide application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a metallographic photograph of the Stellite alloy coating obtained in Embodiment 1 of the present invention after semi-remelting and solidification. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] This embodiment provides a method for preparing Stellite alloy coatings, including the following steps:

[0029] Preheating and heat preservation: The original Stellite alloy coating and its substrate are placed in a vacuum furnace and preheated to 100-300℃ and then kept at that temperature. The ratio of coating thickness to substrate thickness is called the thickness ratio. The heat preservation time is positively correlated with the thickness ratio; the larger the ratio of coating thickness to substrate thickness, the longer the heat preservation time. Further, the heat preservation temperature range can be 150-250℃; even further, the heat preservation temperature range can be 175-225℃; specifically, the heat preservation temperature can be 100℃, 125℃, 150℃, 175℃, 200℃, 225℃, 250℃, 275℃, 300℃, or any temperature value between two of the above.

[0030] Semi-remelting and solidification: The coating surface is remelted at a temperature 20%–35% of the melting point of the Stellite alloy, and the melt is allowed to solidify. Further, a temperature 25%–30% of the melting point of the Stellite alloy can be used as the remelting temperature; specifically, the remelting temperature can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% of the melting point of the Stellite alloy, or any percentage between two percentages. Remelting the Stellite alloy coating at a temperature lower than the melting point of the Stellite alloy ensures that the melt has a certain degree of flowability, effectively avoids uneven coating thickness caused by the melt flowing everywhere, and improves preparation efficiency. Experimental data also shows that the resulting Stellite alloy coating exhibits excellent wear and corrosion resistance.

[0031] After the first pass of semi-remelting and solidification is completed and the coating has cooled to 100–300°C, N more passes of semi-remelting and solidification are performed following the same steps, where N is a natural number and 0 ≤ N ≤ 5. Furthermore, the value of N is in the range of 2 ≤ N ≤ 5; specifically, N can be 0, 1, 2, 3, 4, or 5. Multiple passes of semi-remelting and solidification can more thoroughly refine the grains while effectively avoiding cracking and other phenomena caused by excessive passes.

[0032] Cooling: After all passes of semi-remelting and solidification are completed, the coating is cooled to room temperature to obtain a Stellite alloy coating. Further, after the solidification of the last pass, the coating can be allowed to cool naturally to room temperature. Preferably, after the coating has cooled to room temperature, the coating surface is cleaned.

[0033] The Stellite alloy coating preparation method provided in this embodiment remelts the existing Stellite alloy coating at a temperature lower than the melting point of Stellite alloy, making the grains of the Stellite alloy coating finer and the bonding with the substrate better. Under the action of abrasion, its weight loss is reduced by more than half. Therefore, the Stellite alloy coating preparation method provided by this invention can significantly improve the abrasion resistance of Stellite alloy coating, which is of great significance for the full application of Stellite alloy.

[0034] Specifically, in this embodiment, K is set as the thickness ratio, that is, the ratio of the coating thickness to the substrate thickness. If K≤1 / 5, the heat preservation time is 30 to 60 minutes, which can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, or any time between two points.

[0035] If 1 / 5 < K < 1 / 2, the heat preservation time is 90 to 150 minutes, specifically 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, 150 minutes, or any time between two points. Preferably, the heat preservation time is 120 minutes.

[0036] If 1 / 2≤K≤1, the heat preservation time is 180~210min, specifically 180min, 190min, 200min, 210min, or any time between two points. Preferably, the heat preservation time is 200min.

[0037] If K > 1, the heat preservation time is 240 to 300 minutes, specifically 240 minutes, 250 minutes, 260 minutes, 270 minutes, 280 minutes, 290 minutes, 300 minutes, or any time between two points. Preferably, the heat preservation time is 250 minutes.

[0038] Specifically, in this embodiment, during the preheating and heat preservation process, the heating rate of both the original Stellite alloy coating and its substrate is controlled to be no higher than 100℃ / h. Further, the heating rate can be 50–100℃ / h, specifically 50℃ / h, 75℃ / h, 100℃ / h, or any heating rate between two values. A suitable heating rate ensures preparation efficiency and effectively avoids uneven heating and stress concentration caused by excessively rapid heating.

[0039] Specifically, in this embodiment, during both the preheating and heat preservation processes, a protective gas is introduced into the vacuum furnace, and the flow rate of the protective gas is controlled to be 0.5–5 ml / min. Further, the flow rate of the protective gas can be 0.5–3.5 ml / min, and even further, it can be 0.5–2 ml / min. Specifically, the flow rate of the protective gas can be 0.5 ml / min, 1 ml / min, 1.5 ml / min, 2 ml / min, 2.5 ml / min, 3 ml / min, 3.5 ml / min, 4 ml / min, 4.5 ml / min, 5 ml / min, or any flow rate between two specified values.

[0040] Specifically, in this embodiment, during both the semi-remelting and solidification processes, a protective gas is blown onto the molten surface, and the flow rate of the protective gas is controlled to be no less than 15 ml / min. Further, the flow rate of the protective gas can be 15–35 ml / min, and even further, it can be 15–25 ml / min. Specifically, the flow rate of the protective gas can be 15 ml / min, 16 ml / min, 17 ml / min, 18 ml / min, 19 ml / min, 20 ml / min, 21 ml / min, 22 ml / min, 23 ml / min, 24 ml / min, 25 ml / min, and any flow rate between two specified values.

[0041] Preferably, in this embodiment, argon is selected as the protective gas. Of course, other inert gases, such as krypton, can also be introduced.

[0042] Specifically, in this embodiment, during the semi-remelting process, the coating can be remelted by laser or by induction heating.

[0043] Specifically, in this embodiment, before preheating, the surface of the original Stellite alloy coating is cleaned until the surface roughness Ra is no higher than 100. Cleaning the original coating surface thoroughly removes impurities, ensuring the purity of the final coating and thus guaranteeing its performance. A smaller surface roughness Ra is more conducive to forming a fine and dense coating, thereby improving the coating's wear and corrosion resistance. Further, the surface roughness Ra can be 30–100; even further, it can be 50–100; specifically, the surface roughness Ra can be 50–65, 55–70, 60–75, 65–80, 70–85, 75–90, 80–95, 85–100, 90–100, or other surface roughness ranges.

[0044] Specifically, in this embodiment, acetone is used to clean the surface of the original Stellite alloy coating. Of course, in other embodiments of this application, other solvents can also be used to clean the original Stellite alloy coating, as long as they do not react with it and can clean it thoroughly. This application does not limit the solvents used.

[0045] This embodiment also provides a Stellite alloy coating, which is prepared by the Stellite alloy coating preparation method described above.

[0046] The Stellite alloy coating provided in this embodiment has finer grains and better adhesion to the substrate compared with existing Stellite alloy coatings. Under abrasion, the weight loss is reduced by more than half, and the abrasion resistance is significantly improved, making it suitable for a wide range of applications.

[0047] To further illustrate the present invention, the method for preparing Stellite alloy coating and the Stellite alloy coating provided by the present invention will be described in more detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0048] Example 1

[0049] S110 involves selecting a Stellite 12 coating prepared on a Q235 steel substrate, cleaning its surface with acetone until a glossy surface appears, and ensuring that the surface roughness Ra of the coating is approximately 90–100.

[0050] S120: The substrate from step S110 and the coating prepared on its surface are placed together in a vacuum furnace and preheated to 200°C. The holding time depends on the ratio K of the coating thickness to the substrate thickness. In this embodiment, the ratio K of the coating thickness to the substrate thickness is approximately K≤1 / 5. The holding time is 30-60 minutes, and the heating rate is 100°C / h. Argon gas protection is used during both heating and holding processes, and the argon gas flow rate is 0.5 ml / min.

[0051] S130 is used to perform laser semi-remelting on the coating surface. The remelting temperature is 20% of the melting point of Stellite alloy. The remelting and solidification processes are protected by argon blowing on the surface at a flow rate of 15 ml / min. After remelting, the surface is allowed to cool naturally.

[0052] S140: After the first remelting solidification was completed and cooled to 200°C, four more remelting passes were performed as required by step S130. Figure 1 The image shows a metallographic photograph of the Stellite alloy coating obtained in Example 1 after semi-remelting and solidification. After the last semi-remelting and solidification pass was completed and the coating was cooled to room temperature, the coating surface was cleaned.

[0053] High-temperature friction and wear tests were conducted at 850°C, and it was found that compared with unremelted Stellite 12, the volume loss caused by wear and oxidation corrosion of the Stellite alloy coating prepared in Example 1 was reduced by more than half. The specific results are shown in Table 1.

[0054] Table 1

[0055] Unremelted Stellite 12 coating Remelted Stellite 12 coating <![CDATA[Abrasive volume loss (mm 3 / h)]]> 6.32 3.10

[0056] Example 2

[0057] S210 involves preparing a Stellite 21 alloy coating on a carbon steel substrate, cleaning its surface with acetone until a glossy surface appears, and ensuring that the surface roughness Ra of the coating is approximately 70–85.

[0058] S220: The substrate from step S210 and the coating prepared on its surface are placed together in a vacuum furnace and preheated to 150°C. The holding time depends on the ratio K of the coating thickness to the substrate thickness. In this embodiment, the ratio of the coating thickness to the substrate thickness is approximately 1 / 5 < K < 1 / 2. The holding time is 120 min, and the heating rate is 75°C / h. Argon gas protection is used during both heating and holding processes, and the argon gas flow rate is 2 ml / min.

[0059] S230 is used to perform laser semi-remelting on the coating surface. The remelting temperature is 25% of the melting point of Stellite alloy. The remelting and solidification processes are protected by argon blowing on the surface at a flow rate of 20 ml / min. After remelting, the surface is allowed to cool naturally.

[0060] S240: After the first remelting pass solidified and cooled to 150°C, three more remelting passes were performed as required by step S230. After the last half-remelting and solidification pass was completed and cooled to room temperature, the coating surface was cleaned.

[0061] High-temperature friction and wear tests were conducted at 850°C, and it was found that compared with unremelted Stellite 21, the Stellite alloy coating prepared in Example 2 had a volume loss of more than half due to wear and oxidation corrosion. The specific results are shown in Table 2.

[0062] Table 2

[0063] Unremelted Stellite 21 coating Remelting the Stellite 21 coating <![CDATA[Abrasion volume loss (mm 3 / h)]]> 5.91 2.51

[0064] Example 3

[0065] S310 involves selecting a Stellite 712 alloy coating prepared on a carbon steel substrate, cleaning its surface with acetone until a glossy surface appears, and ensuring that the surface roughness Ra of the coating is approximately 55–70.

[0066] S320: The substrate from step S310 and the coating prepared on its surface are placed together in a vacuum furnace and preheated to 300°C. The holding time depends on the ratio K of the coating thickness to the substrate thickness. In this embodiment, the ratio of the coating thickness to the substrate thickness is approximately 1 / 2 ≤ K ≤ 1. The holding time is 120 min, and the heating rate is 50°C / h. Argon gas protection is used during both heating and holding processes, and the argon gas flow rate is 5 ml / min.

[0067] S330 is used to perform laser semi-remelting on the coating surface. The remelting temperature is 35% of the melting point of Stellite alloy. The remelting and solidification processes are protected by argon blowing on the surface at an argon flow rate of 25 ml / min. After remelting, the surface is allowed to cool naturally.

[0068] S340: After the first remelting and solidification was completed and cooled to 300°C, two more remelting passes were performed as required by step S330. After the last half-remelting and solidification was completed and cooled to room temperature, the coating surface was cleaned.

[0069] High-temperature friction and wear tests were conducted at 850°C, and it was found that compared with unremelted Stellite 712, the volume loss due to wear and oxidation corrosion of the Stellite alloy coating prepared in Example 3 was reduced by more than half. The specific results are shown in Table 3.

[0070] Table 3

[0071] Unremelted Stellite 712 coating Remelted Stellite 712 coating <![CDATA[Abrasion volume loss (mm 3 / h)]]> 5.40 2.11

[0072] Example 4

[0073] S410 involves selecting a Stellite 1 alloy coating prepared on a P92 steel substrate, cleaning its surface with acetone until a glossy surface appears, and ensuring that the surface roughness Ra of the coating is approximately 60–75.

[0074] S420: The substrate from step S410 and the coating prepared on its surface are placed together in a vacuum furnace and preheated to 100°C. The holding time depends on the ratio K of the coating thickness to the substrate thickness. In this embodiment, the ratio of the coating thickness to the substrate thickness is approximately 1 / 5 < K < 1 / 2. The holding time is 120 min, and the heating rate is 100°C / h. Argon gas protection is used during both heating and holding processes, with an argon gas flow rate of 1 ml / min.

[0075] S430 is used to induction heat the coating surface for semi-remelting. The remelting temperature is 35% of the melting point of Stellite alloy. The remelting and solidification processes are protected by argon blowing on the surface at a flow rate of 15 ml / min. After remelting, the surface is allowed to cool naturally.

[0076] In step S440, after the first remelting pass solidified and cooled to 100°C, five more remelting passes were performed as required by step S430. After the last half-remelting and solidification pass was completed and cooled to room temperature, the coating surface was cleaned.

[0077] High-temperature friction and wear tests were conducted at 850°C, and it was found that compared with unremelted Stellite 1, the Stellite alloy coating prepared in Example 4 had a volume loss of more than half due to wear and oxidation corrosion. The specific results are shown in Table 4.

[0078] Table 4

[0079] Unremelted Stellite 1 coating Remelted Stellite 1 coating <![CDATA[Abrasion volume loss (mm 3 / h)]]> 8.21 3.95

[0080] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0081] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a Stellite alloy coating, characterized in that, Includes the following steps: Preheating and heat preservation: The original Stellite alloy coating and its substrate are placed in a vacuum furnace and preheated to 100~300℃ and kept at that temperature. The ratio of coating thickness to substrate thickness is called the thickness ratio, and the heat preservation time is positively correlated with the thickness ratio. Semi-remelting and solidification: The coating surface is remelted at a temperature of 20% to 35% of the melting point of Stellite alloy and the melt is allowed to solidify. During the semi-remelting process, the coating is remelted by laser or induction heating. After the first pass of semi-remelting and solidification is completed and the coating has cooled to 100~300℃, N passes of semi-remelting and solidification are performed again according to the above steps, where N is a natural number and 0≤N≤5. Cooling: After all passes of semi-remelting and solidification are completed, the coating is cooled to room temperature to obtain the Stellite alloy coating.

2. The method for preparing Stellite alloy coating according to claim 1, characterized in that, The range of N is: 2≤N≤5.

3. The method for preparing Stellite alloy coating according to claim 1 or 2, characterized in that, If K≤1 / 5, the heat preservation time is 30~60min; If 1 / 5 < K < 1 / 2, then the heat preservation time is 90~150 minutes; If 1 / 2≤K≤1, then the heat preservation time is 180~210min; If K > 1, the heat preservation time is 240~300 min; where K is the thickness ratio.

4. The method for preparing Stellite alloy coating according to claim 1 or 2, characterized in that, During the preheating and heat preservation process, the heating rate of the original Stellite alloy coating and its substrate is controlled to be no higher than 100℃ / h.

5. The method for preparing Stellite alloy coating according to claim 1 or 2, characterized in that, During the preheating and heat preservation processes, a protective gas is introduced into the vacuum furnace, and the flow rate of the protective gas is controlled at 0.5~5 ml / min.

6. The method for preparing Stellite alloy coating according to claim 1 or 2, characterized in that, During both the semi-remelting and solidification processes, protective gas is blown onto the molten surface, and the flow rate of the protective gas is controlled to be no less than 15 ml / min.

7. The method for preparing Stellite alloy coating according to claim 1 or 2, characterized in that, Before preheating, the surface of the original Stellite alloy coating is cleaned until the surface roughness Ra is not higher than 100.

8. The method for preparing Stellite alloy coating according to claim 7, characterized in that, During cleaning, acetone is used to clean the surface of the original Stellite alloy coating.

9. A Stellite alloy coating, characterized in that, It is prepared by the Stellite alloy coating preparation method according to any one of claims 1-8.

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