JP2014083587A - Surface treatment method of metallic material and metal mold for die cast - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment method of a metallic material for imparting seizure resistance to a molten aluminum alloy in this metallic material, by forming a coating film on a surface of the metallic material.SOLUTION: After forming a connection layer on a melting damage resistant layer formed on the surface of the metallic material, in order from the melting damage resistant layer side, a TiSiN layer as a nitride film of a film thickness of 0.5 μm connected to the melting damage resistant layer is formed separately from the connection layer in a first step. A TiSiO layer as an inclination film of a film thickness of 2.0 μm with an increased oxygen amount and a reduced nitrogen amount is formed as an intermediate layer in a second step. A TiSiON layer as an oxide film of a film thickness of 0.5 μm is formed as an oxide layer with enhanced adhesion property in a third step. As a result, a seizure resistant layer including TiSiO of a three-layer structure is formed.

Description

  The present invention provides a surface treatment method for a metal material that imparts seizure resistance to a molten aluminum alloy to a metallic material serving as a base material for a die casting die that comes into contact with the molten aluminum alloy by forming a film on the surface; The present invention relates to a die casting mold in which a molding surface is processed by this method.

  The cast aluminum molded product is obtained by pressing a molten metal such as an aluminum alloy into a molding hole of a die casting die, solidifying it, and taking it out. When the molded product is baked on the molding surface at the time of taking out, it is difficult to release the mold, which is known to cause deterioration in dimensional accuracy of the cast product and decrease in productivity. For this reason, the performance required for the die casting mold includes seizure resistance and galling resistance for preventing galling caused by the progress of seizure.

  As a method of suppressing such seizure and galling, a method of changing the mold design and casting conditions and reducing the mold temperature during casting is conventionally known. In addition, there is a method of applying a release agent to temporarily give a surface film to the mold surface (for example, Patent Document 1 below). In addition to these, a change in the material of the mold for improving the resistance to seizure has been studied. Further, in the invention according to Patent Document 2 below, a die casting die for forming a composite oxide film made of Al-Cr-Si-Fe on the die design surface by repeatedly casting a molten aluminum alloy while supplying Si element to the outside. A method for improving the seizure resistance has been proposed. Patent Document 3 below proposes an invention relating to a die casting die which is intended to provide seizure resistance by coating an oxide film on the surface.

JP 2007-1108035 A JP 2011-255411 A JP 2010-58135 A

  As described above, regarding surface treatments such as die casting molds for forming cast aluminum molded products, it is required to impart seizure resistance and galling resistance, and various technological developments are underway. There is no definitive means to solve it. In view of this situation, the inventors have intensively studied, and by forming a predetermined oxide film on the surface of the metal material, a metal that can impart excellent seizure resistance and galling resistance to the metal material. It came to create the surface treatment method of the material.

  Therefore, the present invention provides a surface treatment method for a metal material that makes it possible to impart excellent seizure resistance and galling resistance to the surface of the metal material that is the base material of the die casting die that comes into contact with the molten aluminum alloy. An object of the present invention is to provide a die casting mold having a molding surface treated by this method.

  In order to achieve the above object, the present invention provides a surface treatment method for a metal material, which forms a film on the surface of the metal material and imparts seizure resistance to the molten aluminum alloy to the metal material. On the surface, an oxide composed of one or more elements selected from four elements of Ti, Si, Al, and Zr, of which at least one or a combination of two or more oxides excluding TiO A seizure-resistant layer containing the oxide is formed to form a film.

  In particular, the oxide is preferably TiSiO, TiAlO, or ZrO, and more preferably a heat crack resistant layer and a melt resistant layer are formed between the surface of the metal material and the seizure resistant layer. It is also preferable to form a contact layer that eliminates these interfaces between the melt-resistant layer and the seizure-resistant layer and to configure the seizure-resistant layer as a three-layer structure.

  The present invention also includes a die-casting die having a metal material as a base material, the die-casting die having a molding surface treated by the surface treatment method for a metal material according to the present invention. .

  The inventors of the present invention provide an oxide composed of one or more elements selected from four elements of Ti, Si, Al, and Zr on the surface of a metal material, and at least one of oxides excluding TiO. Confirm that this metal material has excellent seizure resistance against molten aluminum alloy by forming a film with a seed or a combination of two or more, and forming a seizure-resistant layer containing such an oxide. did. In particular, the above compounds are TiSiO, TiAlO, and ZrO, and it is found that when the film is formed by one or a combination of two or more selected from these compounds, the most remarkable seizure resistance to the molten aluminum alloy is obtained. It was. Therefore, this invention can provide the surface treatment method of the metal material for setting it as the metal material provided with the seizure resistance outstanding with respect to the aluminum alloy molten metal.

  In particular, in the present invention, by forming a heat crack resistant layer and a melt resistant layer between the surface of the metal material and the seizure resistant layer, various coatings such as a base material and a seizure resistant layer are formed by the heat crack resistant layer. Based on the difference in thermal expansion, it is possible to suppress the occurrence of cracks in the coating, and it is possible to prevent the molten aluminum alloy from entering the base material and causing the base material to melt due to the anti-melting layer. . Further, by forming a jump layer that eliminates these interfaces between the melt-resistant layer and the seizure-resistant layer, the adhesion between the melt-resistant layer and the seizure-resistant layer can be improved. By constituting the seizure-resistant layer as a three-layer structure, adhesion of the seizure-resistant layer itself can be obtained and stable film formation can be achieved. Therefore, this invention can provide the surface treatment method of the metal material for setting it as the metal material provided with the further outstanding performance with respect to aluminum alloy molten metal.

  Furthermore, since the present invention includes a die casting mold in which a molding surface is treated by such a metal material surface treatment method, the present invention provides a die casting mold having excellent performance with respect to molten aluminum alloy. be able to.

It is a schematic diagram which illustrates typically the example of the seizure-proof layer produced with the surface treatment method of the metal material which concerns on this invention. It is sectional drawing which shows typically the experimental apparatus for evaluating the seizure resistance about the seizure resistance layer produced by the surface treatment method of the metal material according to the present invention. It is explanatory drawing which shows the evaluation result of the seizure resistance about the seizure resistance layer produced by the surface treatment method of the metal material concerning the present invention, and (a) comprises the seizure resistance which example 1 was excellent in. It is explanatory drawing which shows doing, (b) is explanatory drawing which shows that the comparative example 1 is seized with respect to aluminum alloy molten metal. It is a mimetic diagram used as a standard which judges with a Rockwell impression test about a seizure-proof layer produced by a surface treatment method of a metallic material concerning the present invention.

  Hereinafter, the present invention will be described in detail. The present invention is a surface treatment method for a metal material, in which a film is formed on the surface of the metal material, and the metal material is given seizure resistance against molten aluminum alloy. The metal material is mainly hot die steel (C, Si, Mn, P, S, Ni, Cr, Mo, W, V, Co, and other elements containing trace elements such as die casting die base material) Steel, so-called SKD61), is exemplified, and in the following description, an example using SKD61 will be described.

  In the surface treatment method for a metal material according to the present invention, for example, the surface of a round bar-shaped SKD 61 is an oxide composed of one or more elements selected from four elements of Ti, Si, Al, and Zr. Of these, a film is formed of at least one oxide or a combination of two or more oxides excluding TiO, and a seizure-resistant layer containing this oxide is formed. In particular, an oxide of TiSiO, TiAlO, or ZrO is formed on the surface of SKD61. Further, a heat crack resistant layer is formed on the surface of the SKD 61, a melt resistant layer is formed on the heat crack resistant layer, and a seizure resistant layer is formed on the resistant layer. Thereby, in addition to the seizure resistance with respect to molten aluminum alloy, heat crack resistance and melt resistance can be imparted to SKD61.

  Further, when forming a seizure-resistant layer on the anti-scratch layer, a jump layer for eliminating the interface between these layers is formed. As the jump layer, any one of TiSiN, TiAlN, and ZrN may be selected in accordance with the oxide of the seizure-resistant layer to be formed.

  The seizure-resistant layer is formed so as to have a three-layer structure. Specifically, when obtaining a seizure-resistant layer containing TiSiO, the TiSiN layer, the TiSiON layer, and the TiSiO layer are formed in this order from the melt-resistant layer (spinning layer) side. As a result, the seizure-resistant layer has sufficient adhesion. In addition, it becomes possible to stably form a seizure-resistant layer. When obtaining a seizure-resistant layer containing TiAlO, a TiAlN layer, a TiAlON layer, and a TiAlO layer are formed in this order from the melt-resistant layer (spinning layer) side, and when obtaining a seizure-resistant layer containing ZrO, The ZrN layer, the ZrON layer, and the ZrO layer are formed in this order from the (cover layer) side.

  In addition, as long as the seizure-resistant layer can obtain a desired seizure resistance to the molten aluminum alloy, one type of oxide is formed as described above, and the seizure-resistant layer containing this oxide is formed. Two or more types of oxides may be combined to form a seizure-resistant layer containing these oxides. That is, a metal material surface treatment method in which two or more kinds of films are selected from TiSiO, TiAlO, and ZrO and a seizure-resistant layer containing these oxides is formed is also included in the present invention.

  Here, the background of finding TiSiO, TiAlO, and ZrO as oxides that form a seizure-resistant layer capable of obtaining desired seizure resistance will be described. First, a candidate oxide can be an oxide that does not react or hardly reacts with aluminum. This is because even if an oxide that reacts with aluminum is formed on the surface of the metal material, it chemically reacts with the molten aluminum alloy and is released from the surface and peeled off, and the metal material itself is exposed and seizure occurs. .

  Next, if the conventional mold release agent reacts with the molten aluminum alloy and the die casting mold surface at a high temperature, a black oxide film is formed on the die casting mold surface to prevent seizure. Silicon oxide can be regarded as a promising candidate. Furthermore, from the knowledge that ceramics and aluminum have low affinity (low wettability), an oxide of aluminum or zirconium can be regarded as a promising candidate. Based on these reasons, candidate oxides were narrowed down to find TiSiO, TiAlO, and ZrO.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are merely examples embodying the configuration of the present invention, and the present invention can be modified in various ways without departing from the matters described in the claims. . Here, a procedure for forming a seizure-resistant layer containing TiSiO and obtaining a round rod material of SKD61 (Example 1) imparted with seizure resistance against molten aluminum alloy will be described.

  First, a heat crack resistant layer made of a Cr layer is formed on the surface of the round bar of SKD61.

<Film-forming conditions for heat crack resistant layer>
Heater: 750 ° C
Time: 10 minutes Bias voltage: 15V
Furnace pressure: 2.6Pa
Arc current: Cr target 100A
Coil current: 50A
Ar gas 300ccm

  Further, an anti-scratch layer in which CrN layers and Cr layers are alternately stacked is formed on the formed heat crack resistant layer.

<Filming conditions for the melt resistant layer>
Heater: 750 ° C
Time: CrN layer 30 minutes, Cr layer 3 minutes 10 times in total Bias voltage: 15V
Furnace pressure: 2.6Pa
Arc current: Cr target 100A
Coil current: 50A
Ar gas 300ccm
N ₂ gas 300ccm

  Next, a jump layer for eliminating the interface between the erosion resistant layer and the seizure proof layer is formed on the formed erosion resistant layer.

<Conditions for forming the jump layer>
Heater: 750 ° C
Time: CrN layer 3 minutes, TiSiN layer 3 minutes Bias voltage: 30V
Furnace pressure: 2.6Pa
Arc current: Cr target 100A, TiSi target 100A
Coil current: 50A
N ₂ gas 400ccm

  A seizure-resistant layer is formed on the formed jump layer. The anti-seizure layer is formed in three steps to form a three-layer structure.

<Filming conditions for seizure-resistant layer>
(1) First step Heater: 750 ° C
Time: TiSiN layer 10 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: TiSi target 100A
Coil current: 50A
N ₂ gas 300ccm

(2) Second step heater: 750 ° C
Time: TiSiON layer 20 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: TiSi target 100A
Coil current: 50A
N ₂ gas 170ccm
O ₂ gas 130ccm

(3) Third step heater: 750 ° C
Time: TiSiO layer 10 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: TiSi target 100A
Coil current: 50A
O ₂ gas 200ccm
Ar gas 100ccm

  In this embodiment, in the first step, a 0.5 μm-thick nitride film to be connected to the melt-resistant layer, which is different from the shell layer, is used as an intermediate layer in the second step, and the oxygen amount is increased and the nitrogen amount is decreased. An inclined film having a thickness of 2.0 μm is formed as an oxide film having a thickness of 0.5 μm as an oxide layer having improved adhesion in the third step. Since an oxide film is generally brittle, a nitride film with stable adhesion is formed first, and an oxynitride film is formed by tilting the introduced gas on the basis of this to ensure adhesion, and finally An oxide film is formed. When forming the oxide film, the plasma was stabilized by flowing Ar gas, and a seizure-resistant layer having a three-layer structure could be formed efficiently. A schematic diagram of a seizure-resistant layer produced as described above is shown in FIG.

  According to the manufacturing procedure as described above, round bars (test pieces) of SKD61 according to Examples 1 to 3 and Comparative Example 1 were obtained, and evaluation was made as to whether or not seizure resistance to the molten aluminum alloy was imparted. The contents will be explained.

A. 2. Welding resistance test The test pieces of Examples 1 to 3 and Comparative Example 1 were immersed in crucibles in which ADC12 was melted as an aluminum alloy melt using the experimental apparatus shown in FIG. The test conditions are shown in [Table 1] below, and the test results are shown in [Table 2] below.

  Here, the production procedures and the like of Examples 1 to 3 and Comparative Example 1 test pieces are as follows. In addition, since the heat-crack-resistant layer and the melt-resistant layer in the test pieces of these examples and comparative examples are both formed by the above-described procedure, only the structure of the different seizure-resistant layers and the like will be described.

(Example 1: Preparation procedure of a test piece having a seizure-resistant layer containing TiSiO)
It was produced as described in paragraphs [0026] to [0031] above.

(Example 2: Preparation procedure of test piece having seizure-resistant layer containing TiAlO)
<Conditions for forming the jump layer>
Heater: 750 ° C
Time: CrN layer 3 minutes, TiAlN layer 3 minutes Bias voltage: 30V
Furnace pressure: 2.6Pa
Arc current: Cr target 100A, TiAl target 100A
Coil current: 50A
N ₂ gas 400ccm
<Filming conditions for seizure-resistant layer>
(1) First step Heater: 750 ° C
Time: TiAlN layer 10 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: TiAl target 100A
Coil current: 50A
N ₂ gas 300ccm
(2) Second step heater: 750 ° C
Time: TiAlON layer 20 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: TiAl target 100A
Coil current: 50A
N ₂ gas 170ccm
O ₂ gas 130ccm
(3) Third step heater: 750 ° C
Time: TiAlO layer 10 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: TiAl target 100A
Coil current: 50A
O ₂ gas 200ccm
Ar gas 100ccm

(Example 3: Preparation procedure of a test piece having a seizure-resistant layer containing ZrO)
<Conditions for forming the jump layer>
Heater: 750 ° C
Time: CrN layer 3 minutes, ZrN layer 3 minutes Bias voltage: 30V
Furnace pressure: 2.6Pa
Arc current: Cr target 100A, Zr target 100A
Coil current: 50A
N ₂ gas 400ccm
<Filming conditions for seizure-resistant layer>
(1) First step Heater: 750 ° C
Time: ZrN layer 10 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: Zr target 100A
Coil current: 50A
N ₂ gas 300ccm
(2) Second step heater: 750 ° C
Time: ZrON layer 20 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: Zr target 100A
Coil current: 50A
N ₂ gas 170ccm
O ₂ gas 130ccm
(3) Third step heater: 750 ° C
Time: ZrO layer 10 minutes Bias voltage: 100V
Furnace pressure: 2.6Pa
Arc current: Zr target 100A
Coil current: 50A
O ₂ gas 200ccm
Ar gas 100ccm

(Comparative example 1: Production procedure of test piece not forming seizure-resistant layer)
The round bar material according to Comparative Example 1 did not form a seizure-resistant layer.

  As a result of the evaluation, as shown in [Table 2] above, it was confirmed that each of the round bar materials of Examples 1 to 3 had good seizure resistance without adhesion of aluminum. On the other hand, adhesion of aluminum was recognized in the round bar material according to Comparative Example 1, and the amount of adhesion increased each time the number of times was increased. From FIG. 3 (a), it is understood that the test piece of Example 1 has good seizure resistance without adhesion of aluminum due to the seizure resistance layer containing TiSiO. From FIG.3 (b), since the test piece of the comparative example 1 does not have seizure resistance, adhesion of aluminum is recognized.

B. Adhesion evaluation test With respect to the test pieces according to Examples 1 to 3 and Comparative Example 1, indentations were made with a Rockwell altimeter, and the peeled state was evaluated. As the evaluation criteria, in the Rockwell indentation test, those in which the peeled state was within the criteria were judged as acceptable, and those outside the criteria were judged as unacceptable. A schematic diagram as a test standard is shown in FIG. The test results are shown in [Table 3] below.

  As a result of the evaluation, as shown in [Table 3] above, it was confirmed that each of the test pieces of Examples 1 to 3 had good adhesion. In addition, since the favorable adhesiveness was shown also about the test piece of the comparative example 1, it is suggested that sufficient effect can be anticipated about melt-resistance.

(Reference example: test piece having a seizure-resistant layer containing TiO)
As a reference example, a test piece having a seizure-resistant layer containing TiO was produced in accordance with the production procedure described above. However, it was judged that the produced test piece was not able to be used as an oxide used in the surface treatment method for a metal material according to the present invention because adhesion of aluminum was recognized in the welding resistance test.

  Therefore, the surface treatment method for a metal material according to the present invention forms a film on the surface of the metal material by using any one of TiSiO, TiAlO, and ZrO, and forms a seizure-resistant layer containing such an oxide. It was confirmed that the metal material has excellent seizure resistance performance against the molten aluminum alloy. Furthermore, by forming a heat crack resistant layer and a corrosion resistant layer between the surface of the metal material and the seizure resistant layer, in addition to seizure resistance, it is possible to further impart heat crack resistance and corrosion resistant property. . Further, by forming a jump layer that eliminates these interfaces between the melt-resistant layer and the seizure-resistant layer, the adhesion between the melt-resistant layer and the seizure-resistant layer can be improved. By forming the seizure-resistant layer in a three-layer structure, the adhesion of the seizure-resistant layer itself was obtained and a stable film formation could be achieved.

  And since what was employ | adopted as a metal material in embodiment (Example) mentioned above is SKD61 widely used as a raw material of a die-casting die, surface treatment of the molding surface of a die-casting die by the present invention, That is, the seizure resistance to the molten aluminum alloy can be imparted to the molding surface of the die-casting die by forming a film by using any one of TiSiO, TiAlO, ZrO, or a combination of two or more selected from these.

The embodiments and examples believed to be the best by the applicant of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments unless departing from the scope of the claims. Without being limited to the form, various design changes can be made. For example, the heat-crack-resistant layer and the melt-resistant layer may be formed by satisfying the desired performance in addition to the above-described examples of the Cr layer, the Cr layer and the CrN layer. Depending on the structure, the composition such as the compound composition can be appropriately changed. Even if it is an oxide other than TiSiO, TiAlO, and ZrO, this oxide can be used if it is an oxide (excluding TiO) composed of one or more elements selected from the four elements of Ti, Si, Al, and Zr. The seizure-resistant layer containing an object can have excellent seizure resistance against molten aluminum alloy. Examples thereof include oxides such as SiO (SiO, SiO ₂ etc.), AlO (Al ₂ O ₃ etc.), TiZrO _x , SiZrO _x , AlZrO _x , TiAlZrO _x , TiSiZrO _x , SiAlZrO _x , TiSiAlZrO _{x and the} like.

1 Test piece 2 Aluminum alloy molten metal 3 Electric furnace 4 Graphite crucible

Claims (6)

A surface treatment method of a metal material that forms a film on the surface of the metal material and imparts seizure resistance to the molten aluminum alloy to the metal material,
On the surface of the metal material, an oxide composed of one or more elements selected from four elements of Ti, Si, Al, and Zr, of which at least one or two of oxides excluding TiO A film is formed by the above combination to form a seizure-resistant layer containing the oxide.
A surface treatment method for a metal material. The oxide is TiSiO, TiAlO, ZrO.
The surface treatment method for a metal material according to claim 1. Between the surface of the metal material and the seizure resistant layer, a heat crack resistant layer and a melt resistant layer are formed.
The surface treatment method for a metal material according to claim 1 or 2, characterized in that Between the melt-resistant layer and the seizure-resistant layer, a jump layer that eliminates these interfaces is formed.
The surface treatment method for a metal material according to claim 3. Configuring the seizure-resistant layer as a three-layer structure;
The surface treatment method for a metal material according to any one of claims 1 to 4, wherein:   A die-casting die having the metal material as a base material, wherein a molding surface is treated by the surface treatment method for a metal material according to any one of claims 1 to 5. Die casting mold.