阅读说明：本技术 在铸造金属件表面制备金属覆层的前处理方法、铸造金属件金属覆层零部件及其制备方法 (Pretreatment method for preparing metal coating on surface of cast metal piece, cast metal piece metal coating part and preparation method thereof ) 是由 李宝增 程宝改 谢美芳 张红恩 林生军 庞亚娟 苗晓军 李新刚 张颖杰 田鹏 陈 于 2019-10-14 设计创作，主要内容包括：本发明涉及一种在铸造金属件表面制备金属覆层的前处理方法、铸造金属件金属覆层零部件及其制备方法,属于铸造金属件金属覆层零部件的制备技术领域。本发明的在铸造金属件表面制备金属覆层的前处理方法,包括对铸造金属件进行表面处理使其表面致密化。本发明的在铸造金属件表面制备金属覆层的前处理方法,通过对铸造金属件表面进行表面处理,将铸造金属件的表面进行致密化处理,大量消除针孔缺陷,强化其表面组织形态,可以为后续制备金属覆层提供更优的基体,提高金属覆层与铸造金属件的结合力。(The invention relates to a pretreatment method for preparing a metal coating on the surface of a cast metal piece, a cast metal piece metal coating part and a preparation method thereof, belonging to the technical field of preparation of cast metal piece metal coating parts. The pretreatment method for preparing the metal coating on the surface of the cast metal piece comprises the step of carrying out surface treatment on the cast metal piece to densify the surface of the cast metal piece. According to the pretreatment method for preparing the metal coating on the surface of the cast metal piece, disclosed by the invention, the surface of the cast metal piece is subjected to densification treatment by performing surface treatment on the surface of the cast metal piece, so that a large number of pinhole defects are eliminated, the surface structure form of the cast metal piece is strengthened, a better matrix can be provided for the subsequent preparation of the metal coating, and the bonding force between the metal coating and the cast metal piece is improved.)

1. A pretreatment method for preparing a metal coating on the surface of a cast metal piece is characterized by comprising the following steps: comprising surface treating the cast metal article to densify the surface thereof.

2. The pretreatment method for preparing a metal coating on the surface of a cast metal piece according to claim 1, wherein the pretreatment method comprises the following steps: the surface treatment is rolling treatment.

3. The pretreatment method for preparing a metal coating on the surface of a cast metal piece according to claim 2, wherein the pretreatment method comprises the following steps: the rolling treatment enables the pressing size of a single surface of the cast metal piece to be 100-200 mu m.

4. The pretreatment method for preparing a metal coating on the surface of a cast metal piece according to claim 1, wherein the pretreatment method comprises the following steps: and removing residual stress of the cast metal piece after surface treatment.

5. The pretreatment method for preparing a metal coating on the surface of a cast metal piece according to claim 1, wherein the pretreatment method comprises the following steps: and machining the cast metal piece after surface treatment before removing the residual stress.

6. The pretreatment method for preparing the metal coating on the surface of the cast metal piece according to any one of claims 1 to 5, wherein the pretreatment method comprises the following steps: and the step of removing the residual stress is to heat the cast metal piece at 150-160 ℃.

7. The pretreatment method for preparing a metal coating on the surface of a cast metal piece according to claim 1, wherein the pretreatment method comprises the following steps: the cast metal piece is a cast aluminum alloy piece.

8. A preparation method of a metal coating part of a cast metal piece is characterized by comprising the following steps: the method comprises the following steps of carrying out surface treatment on a cast metal piece to densify the surface of the cast metal piece, and then removing residual stress; and then preparing a metal coating on the surface of the cast metal piece to obtain the metal casting.

9. The method of making a cast metal article metal-clad component part of claim 8, wherein: the metal coating is silver.

10. A cast metal part having a metal coating made by the method of claim 8.

Technical Field

The invention relates to a pretreatment method for preparing a metal coating on the surface of a cast metal piece, a cast metal piece metal coating part and a preparation method thereof, belonging to the technical field of preparation of cast metal piece metal coating parts.

Background

The casting and forming process has a long history, and the casting blank can achieve the purpose of avoiding machining or reducing machining due to the fact that the casting blank is almost formed, so that the casting and forming become one of basic processes of the modern mechanical manufacturing industry. Cast metal parts are obtained by casting and molding, and surface treatment is often needed in order to meet the requirements of corrosion resistance, wear resistance, decoration or other special functions of products. Such as cast aluminum alloy, are widely used in high-voltage switch conductive circuits for improving the conductivity thereofThe contact surface is generally subjected to silver plating treatment, and in order to ensure that the quality of the silver plating layer meets the use requirement, the silver plating pretreatment is generally carried out by' part forming → degreasing → water washing → alkaline etching → hot water washing → mixed acid washing (HF + HNO)₃) And a plurality of processes such as water washing and the like are performed to thoroughly clean the residual oil stains and the generated oxide scale on the surface of the component, so that the bonding force between the silver coating layer of the component and the component substrate is improved. However, the silver plating layer obtained by silver plating after the pretreatment process is prone to peeling, and particularly, such problems are more likely to occur under the condition of heating, and are not allowed in production. Not only are aluminum alloys cast, but also the metal coatings prepared on the surfaces of other cast metal parts are often blister peeled.

At present, most researches improve the bonding force between a cast metal part substrate and a coating layer by changing pretreatment process parameters, such as prolonging the pickling time, increasing the cleaning times and the like.

Disclosure of Invention

The invention aims to provide a pretreatment method for preparing a metal coating on the surface of a cast metal piece, which can improve the bonding force between the cast metal piece and the metal coating and reduce the occurrence of metal coating blistering.

The invention also provides a cast metal part metal coating part and a preparation method thereof.

In order to achieve the purpose, the technical scheme adopted by the pretreatment method for preparing the metal coating on the surface of the cast metal piece is as follows:

a pretreatment method for preparing a metal coating on the surface of a cast metal piece comprises the step of carrying out surface treatment on the cast metal piece to densify the surface of the cast metal piece.

According to the pretreatment method for preparing the metal coating on the surface of the cast metal piece, disclosed by the invention, the surface of the cast metal piece is subjected to densification treatment by performing surface treatment on the surface of the cast metal piece, so that a large number of pinhole defects are eliminated, the surface structure form of the cast metal piece is strengthened, a better matrix can be provided for the subsequent preparation of the metal coating, and the bonding force between the metal coating and the cast metal piece is improved.

Preferably, the surface treatment is a rolling treatment. The rolling treatment can form a continuous densified layer on the surface of the cast metal piece, thereby greatly reducing the probability of pinholes in the densified layer and enabling the thickness of the prepared metal coating to be more uniform.

In order to ensure that the densified layer on the surface of the cast metal piece has a certain thickness after the cast metal piece is subjected to subsequent treatment such as machining, the rolling treatment is preferably performed to ensure that the pressing size of one side of the cast metal piece is 100-200 μm.

When the cast metal part is subjected to surface treatment, according to different treatment modes, for example, after rolling treatment is adopted, residual stress is generated in a deformation area, and in order to avoid that after a metal coating is prepared on the surface of the cast metal part, the residual stress remained in a cast metal matrix is too large, so that the metal coating generates a bubbling and peeling phenomenon, and the use of the metal coating part of the cast metal part is influenced, preferably, the treatment method further comprises the step of removing the residual stress from the cast metal part after surface treatment.

The treatment method further comprises machining the surface-treated cast metal piece before removing the residual stress. For cast metal parts that require machining, stress problems also arise during machining. The surface of a cast metal part is extruded by a cutter in the machining process, certain deformation can be generated, machining residual stress can accompany in a deformation area, once the cast metal part is formed, subsequent treatment is directly carried out on the cast metal part to prepare a metal coating, the residual stress is remained in a cast metal gold matrix, the residual stress is too large, the phenomenon of bubbling and peeling of the metal coating is caused, the use is influenced, and finally parts of the metal coating of the cast metal part are repaired or scrapped. Therefore, for the cast metal part needing machining, the residual stress is removed after machining, the production process is simplified, and the bubbling and falling of the metal coating caused by machining can be avoided.

And the step of removing the residual stress is to heat the cast metal piece at 150-160 ℃. The heating temperature of 150-160 ℃ is adopted, so that the purpose of removing residual stress can be achieved, and the surface of a cast metal piece can be prevented from being oxidized rapidly and greatly due to overhigh heating temperature.

The preparation method of the metal coating part of the cast metal piece adopts the technical scheme that:

a method for preparing metal coating parts of cast metal parts comprises surface treating the cast metal parts to densify the surface; and then preparing a metal coating on the surface of the cast metal piece to obtain the metal casting.

According to the preparation method of the cast metal part metal coating part, the surface of the cast metal part is densified, so that the phenomenon that the metal coating layer is foamed and falls off due to the fact that gas in a pinhole on the surface of a cast metal part matrix is heated and expanded in the using process of the cast metal part metal coating part is avoided.

Preferably, the metal coating is silver. The preparation method of the cast metal piece metal layer part is particularly suitable for preparing the silver metal coating on the surface of the cast metal piece, can greatly reduce the production cost, improve the binding force between the silver metal coating and the surface of the cast metal piece, and prolong the service life of the part.

The technical scheme adopted by the metal coating part of the cast metal piece is as follows:

the cast metal part metal coating part prepared by the preparation method is provided.

The metal coating part of the cast metal piece has strong bonding force between the metal coating and the cast metal piece substrate, the metal coating is not easy to bubble and fall off, and the service life and the safety of the metal coating part of the cast metal piece are improved.

Detailed Description

The invention provides a pretreatment method for preparing a metal coating on the surface of a cast metal piece, which comprises the step of carrying out surface treatment on the cast metal piece to densify the surface of the cast metal piece.

The pinholes are one of the defects of the cast metal piece, the reason for forming the pinholes by different molten metal is different, but the pinholes are generated by separating out or invading gas, if the surface of the steel casting is mostly columnar crystals, strip-shaped pinholes are easily generated; the cast aluminum alloy is limited by the smelting mode, and pinholes are formed on the surface of a cast part due to inevitable existence of water vapor from smelting raw materials, smelting equipment, climate factors and the like. The pinholes are very small, if the pinholes are not treated, the subsequent conventional metal coating preparation pretreatments such as acid washing and the like are carried out, the pinholes still remain on the surfaces of the manufactured parts, and after the metal coating is covered, the manufactured parts are easy to be heated in the subsequent use process to cause gas expansion inside the pinholes to cause peeling of the metal coating, and particularly, the environments with severe cold and hot circulation and severe corrosive atmosphere are more obvious.

According to the pretreatment method for preparing the metal coating on the surface of the cast metal piece, disclosed by the invention, the surface of the cast metal piece is subjected to densification treatment by performing surface treatment on the surface of the cast metal piece, so that a large number of pinhole defects are eliminated, the surface structure form of the cast metal piece is strengthened, a better matrix can be provided for the subsequent preparation of the metal coating, and the bonding force between the metal coating and the cast metal piece is improved.

Mechanical strengthening can be generally used to densify the surface of the cast metal article. In the coating industry and other industries, sand blasting is generally adopted to strengthen the surface of the cast metal part, but the sand blasting is discontinuous in strengthening the surface of the cast metal part, areas where sand grains are not acted still exist, and pores still exist in the areas after sand blasting; in addition, the surface roughness of the workpiece can reach dozens of microns when being greatly changed by sand blasting, the larger the roughness is, the better the metal coating is, and the bonding force of the coating can be effectively improved by improving the roughness. However, during the forming process of the later-cast metal part, the densified layer is generally partially removed, and during the machining and forming process, the stress generated in the sand blasting process before forming still exists in the part, so that the coating or the coating is easy to release due to the stress during the later-service process, and the coating and the substrate cannot cooperatively deform to generate foaming or peeling phenomena.

Preferably, the surface treatment is a rolling treatment. The rolling treatment can form a continuous densified layer on the surface of the cast metal piece, thereby greatly reducing the probability of pinholes in the densified layer and enabling the thickness of the prepared metal coating to be more uniform.

In order to ensure that the densified layer on the surface of the cast metal piece has a certain thickness after the cast metal piece is subjected to subsequent treatment such as machining, the rolling treatment is preferably performed to ensure that the pressing size of one side of the cast metal piece is 100-200 μm.

When the cast metal part is subjected to surface treatment, according to different treatment modes, for example, after rolling treatment is adopted, residual stress is generated in a deformation area, and in order to avoid that after a metal coating is prepared on the surface of the cast metal part, the residual stress remained in a cast metal matrix is too large, so that the metal coating generates a bubbling and peeling phenomenon, and the use of the metal coating part of the cast metal part is influenced, preferably, the treatment method further comprises the step of removing the residual stress from the cast metal part after surface treatment.

The treatment method further comprises machining the surface-treated cast metal piece before removing the residual stress.

And the step of removing the residual stress is to heat the cast metal piece at 150-160 ℃. The heating temperature of 150-160 ℃ is adopted, so that the purpose of removing residual stress can be achieved, and the surface of a cast metal piece can be prevented from being oxidized rapidly and greatly due to overhigh heating temperature.

Preferably, the heating time is 3-5 h.

Preferably, the cast metal piece is a cast aluminum alloy piece. Because the surface of the cast aluminum alloy has some tiny pinholes which can not be eliminated by the machining treatment in the forming process, the treatment method of the method is adopted to carry out the surfacing treatment on the cast aluminum alloy piece, thereby eliminating a large number of pinholes on the surface of the cast aluminum alloy piece and improving the bonding force between the cast aluminum alloy piece and the metal coating (such as a silver coating).

Preferably, the metal coating is silver. More preferably, the thickness of the metal coating is 20-50 μm.

Preferably, the metal coating is a silver coating.

The invention also provides a preparation method of the metal coating part of the cast metal piece, which comprises the following steps of carrying out surface treatment on the cast metal piece to densify the surface of the cast metal piece; and then preparing a metal coating on the surface of the cast metal piece to obtain the metal casting.

According to the preparation method of the cast metal part metal coating part, the surface of the cast metal part is densified, so that the phenomenon that the metal coating layer is foamed and falls off due to the fact that gas in a pinhole on the surface of a cast metal part matrix is heated and expanded in the using process of the cast metal part metal coating part is avoided.

The metal coating can be prepared on the surface of the cast metal piece by adopting a conventional method in the prior art, such as electroplating, chemical plating, spraying and the like.

Preferably, the surface treatment is a rolling treatment. The rolling treatment enables the pressing size of a single surface of the cast metal piece to be 100-200 mu m.

Preferably, the preparation method further comprises removing residual stress from the surface-treated cast metal piece. And the step of removing the residual stress is to heat the cast metal piece at 150-160 ℃. The heating time is 3-5 h.

Preferably, the above preparation method further comprises machining the surface-treated cast metal member before removing the residual stress. And the part molding can be completed through machining.

Preferably, the cast metal piece is a cast aluminum alloy piece.

Preferably, the metal coating is silver. More preferably, the thickness of the metal coating is 20-50 μm.

Preferably, the metal coating is a silver coating.

Before the metal coating is prepared on the surface of the cast metal piece, the cast metal piece after surface treatment can be subjected to conventional pretreatment before the metal coating is prepared. Preferably, the preparation method further comprises sequentially degreasing and pickling the cast metal piece after the residual stress is removed.

Preferably, after the cast metal piece is degreased, the cast metal piece is sequentially washed by water, alkaline corrosion and water, and then is washed by acid. Furthermore, hot water is adopted for washing after the alkaline etching. Further, before preparing a metal coating on the surface of the cast metal piece, washing the cast metal piece after metal pickling with water.

Preferably, the acid washing is carried out by washing with a mixed acid. The mixed acid is a mixture of nitric acid and hydrofluoric acid.

More preferably, the mixed acid is obtained by mixing 30-50% by mass of hydrofluoric acid, 50-70% by mass of nitric acid and water according to a volume ratio of 2-5: 30-40: 100.

The invention also provides a cast metal part metal coating part prepared by the preparation method.

The metal coating part of the cast metal piece has strong bonding force between the metal coating and the cast metal piece substrate, the metal coating is not easy to bubble and fall off, and the service life and the safety of the metal coating part of the cast metal piece are improved.

The technical solution of the present invention will be further described with reference to the following embodiments.

The mixed acid adopted in each embodiment is prepared by mixing 40 mass percent of hydrofluoric acid, 63 mass percent of nitric acid and H₂And O is mixed according to the volume ratio of 3:40: 100.