JP2016079480A - Member for processing low melting point molten metal excellent in erosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment member excellent in erosion resistance (crack resistance and peeling resistance) to low melting point molten metal, such as solder and aluminum.SOLUTION: A member for processing low melting point molten metal comprises: a titanium oxide layer 5 having a thickness of 2-20 μm on the surface of a base material 7 consisting of titanium; and an oxygen enrichment titanium layer 6 consisting of a α phase having an oxygen concentration higher than that of the base material 7 and having a thickness of 20-200 mum under the titanium oxide layer 5 and is excellent in erosion resistance. An inorganic coating, such as TiO, MgO, SiO, AlOand BN can further be coated on the titanium oxide layer 5. The titanium oxide layer 5 having a thickness of 2-20 μm can be included under the coated layer, and further the oxygen enrichment titanium layer having a α phase having an oxygen concentration higher than that of the base material and a thickness of 20-200 μm can be included under the coated layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a low-melting-point molten metal treated member having excellent melting resistance against low-melting aluminum, lead, tin, and molten metal of each alloy. In particular, the present invention relates to a treatment member that has excellent resistance to melting damage to molten aluminum and its alloys (hereinafter sometimes simply referred to as “aluminum”).

  Processing members such as aluminum casting, a ladle that pumps molten low-melting-point metal and transports it to a mold or die-casting machine, or a scraper that removes “flood” floating on the surface of the molten metal pond is repeatedly melted. Immerse in metal. Moreover, the processing member which protects a temperature measuring apparatus etc. is used in the state immersed in the molten metal.

  In a processing member for handling or processing such a low melting point molten metal, various heat resistant coating agents are applied to the surface of a base material made of cast iron or ceramic to ensure resistance to melting against the low melting point molten metal. .

  However, when the base material is cast iron, the coating agent may be peeled off due to thermal expansion / contraction, and the base material may melt, and the temperature of the molten metal in the ladle is relatively high because the thermal conductivity is relatively high. It tends to decrease, and in addition, the mass is large and the work efficiency may be impaired. When the substrate is made of ceramic, it may be easily broken by impact due to its brittleness, which may impair work efficiency.

In view of this, Patent Document 1 and Patent Document 2 propose titanium processing members using titanium as a base material, which is lighter than cast iron and has a relatively small thermal expansion coefficient and thermal conductivity. As described in Non-Patent Document 1, titanium reacts with aluminum to form TiAl ₃ , so in order to ensure the erosion resistance against molten aluminum, Some surface treatment needs to be applied.

The treatment member of Patent Document 1 is obtained by subjecting titanium of a base material to aluminum plating, and then subjecting the substrate to oxidation treatment in the atmosphere to form an oxide of aluminum, that is, an oxide layer mainly composed of alumina. It is the processing member formed as a protective layer on the surface. However, according to Non-Patent Document 1, it can be said that at least the titanium and aluminum react to form the intermetallic compound TiAl _{3 on} the surface layer of the processing member of Patent Document 1.

The processing member of Patent Document 2 picks up a base material made of titanium or a titanium alloy, then immerses it in molten aluminum to form an aluminum layer on the surface of the base material, and then heat-treats TiAl, TiAl ₂ , TiAl ₃ is a processing member in which an intermetallic compound layer containing at least TiAl ₂ or TiAl ₃ is formed on the surface as a protective layer.

The intermetallic compound of titanium and aluminum (TiAl, TiAl ₂ , TiAl ₃ ) formed on the surface layer of the processing member of Patent Document 1 and Patent Document 2 is a very brittle compound that is easily damaged by impact. In addition, the thermal expansion coefficient of these intermetallic compounds is about 1.5 times greater than that of titanium, so cracks occur in the intermetallic compound layer due to repeated thermal expansion and contraction during use. To do. The molten metal permeates from the cracks, and the processing member is melted.

FIG. 1 shows an intermetallic compound (TiAl ₃ ) layer formed by the reaction of titanium and aluminum on the surface of a titanium substrate immersed in molten aluminum. Cracks 4 are generated in the intermetallic compound (TiAl ₃ ) layer 2. A solidified layer 1 of molten aluminum is formed on the intermetallic compound (TiAl ₃ ) layer 2.

  Even if a heat-resistant coating agent is applied to the surface of the processing member of Patent Document 1 or Patent Document 2, cracks are generated in the intermetallic compound layer due to thermal expansion and contraction, and the intermetallic compound layer is easily peeled off.

  In order to prolong the life of the processing member for the low melting point molten metal, in the protective layer for protecting the processing member, it is possible to suppress the occurrence of cracks due to thermal expansion / contraction or to protect the protective layer. It is necessary to suppress the peeling of the heat-resistant coating layer and to increase the resistance to melting of the processing member with respect to the low melting point molten metal.

Japanese Patent Application Laid-Open No. 08-199322 JP2013-0336070A

Journal of the Japan Institute of Metals, Vol. 64, No. 2, 2000, pages 85-94

  The present invention relates to the generation of cracks in the surface layer of a processing member for handling or processing a low melting point molten metal such as aluminum having a low melting point (hereinafter sometimes referred to as “low melting point molten metal processing member”). A low melting point molten metal treatment with excellent melting resistance that solves the problem by suppressing the peeling of the heat resistant coating layer that protects the surface layer and increasing the resistance to melting of the low melting point molten metal. An object is to provide a member.

  The inventors of the present invention have intensively studied a method for solving the above-described problems. As a result, titanium is used as a base material, and the base material is heat-treated in an atmospheric oxidizing atmosphere to form a titanium oxide layer on the surface of the base material. It has been found that if an oxygen-enriched layer composed of an α phase having a high oxygen concentration is formed, the resistance to melting of the low melting point molten metal-treated member based on titanium with respect to the low melting point molten metal is significantly improved.

  Furthermore, it has been found that if a required heat-resistant coating layer is formed on the outermost surface of the base material, the resistance to melting of the low-melting-point molten metal of the low-melting-point molten metal-treated member based on titanium is further improved.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

  (1) The base material is made of titanium, the surface of the base material has a titanium oxide layer having a thickness of 2 to 20 μm, and under the titanium oxide layer is made of an α phase having a higher oxygen concentration than the base material. A low-melting-point molten metal-treated member excellent in melt resistance, characterized by having an oxygen-enriched layer having a thickness of 20 to 200 μm.

(2) The substrate is made of titanium, and has a coating layer composed of one or more of TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE ₂ O ₃ , and BN on the outermost surface of the substrate. Under the coating layer, a titanium oxide layer having a thickness of 2 to 20 μm is formed, and an oxygen-rich layer having a thickness of 20 to 200 μm is formed under the titanium oxide layer. A processing member for a low-melting-point molten metal having excellent melt resistance, characterized by having a chemical layer.

  (3) The titanium oxide layer and the oxygen-enriched layer are formed by heating the base material in an oxidizing atmosphere at 750 ° C. or higher and lower than 1000 ° C. for 30 minutes or 300 minutes or less. A low-melting-point molten metal treated member having excellent melt resistance as described in (1) or (2).

  (4) Any one of the above (1) to (3), wherein the cross-sectional hardness of the oxygen-enriched layer forms a hardness distribution that continuously decreases from the surface side to the inside of the substrate. A low-melting-point molten metal-treated member having excellent melt resistance as described in 1.

  (5) The low resistance to melt damage according to any one of (1) to (4) above, wherein the 0.2% proof stress at 500 ° C. of titanium used as the substrate is 75 MPa or more. Melting point metal processing member.

  (6) Titanium used as the base material includes Cu: 0.5 to 1.5% by mass, Sn: 1.5% by mass or less, Si: 0.6% by mass or less, and Cu and Sn. The low melting point melting point excellent in melt resistance according to any one of the above (1) to (5), wherein the total amount is 0.5 to 2.7% by mass, and the balance is made of Ti and inevitable impurities Metal processing member.

  ADVANTAGE OF THE INVENTION According to this invention, a base material consists of titanium, The low melting-point molten metal processing member which is excellent in the erosion resistance with respect to low melting-point molten metals, such as low melting-point aluminum, can be provided.

On the surface of the substrate titanium immersed in molten aluminum, which is a diagram showing an intermetallic compound of titanium and aluminum is produced by the reaction (TiAl ₃₎ layer. It is a figure which shows the layer structure (surface layer structure) of the surface layer cross section of this invention. It is a figure which shows the structure | tissue (surface layer structure | tissue) of the surface layer cross section of this invention. It is a figure which shows another layer structure (surface layer structure) of the surface layer cross section of this invention. It is a figure which shows another structure | tissue (surface layer structure | tissue) of the surface layer cross section of this invention. It is a figure which shows the hardness distribution in the cross section of the surface layer part of this invention. It is a figure which shows the reaction layer of titanium and "solder" formed in the surface of base-material titanium.

  The low-melting-point molten metal processing member (hereinafter, simply referred to as “processing member”) repeats thermal expansion / contraction by repeated rise and fall of temperature due to contact with the low-melting-point molten metal. Cracks occur in the surface layer, and the erosion resistance of the processing member to the low melting point molten metal decreases.

  The present inventors diligently researched a treatment member that can maintain excellent melt resistance even when subjected to repeated thermal expansion and contraction.

  As a result, the present inventors used titanium as a base material, heat-treated the base material in an oxidizing atmosphere such as air, and formed a titanium oxide layer on the surface of the base material. If an oxygen-enriched layer consisting of an α phase with a high oxygen concentration is formed, cracks can be prevented from occurring in the titanium oxide layer, which has a high resistance to low-melting-point molten metal, even if the base material repeatedly expands and contracts. It was also found that the adhesion of the heat-resistant coating layer formed on the titanium oxide layer, that is, the peel resistance, can be improved.

The processing member for low melting point molten metal (hereinafter, also referred to as “the processing member of the present invention”) having excellent melt resistance of the present invention based on the above findings is referred to as “the processing member of the present invention”.
(I) The base material is made of titanium, the surface of the base material has a titanium oxide layer having a thickness of 2 to 20 μm, and under the titanium oxide layer, an oxygen phase having a higher oxygen concentration than the base material, It has an oxygen-enriched layer having a thickness of 20 to 200 μm, and
(Ii) The substrate is made of titanium, and a coating layer made of one or more of TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE ₂ O ₃ , and BN is formed on the outermost surface of the substrate. And having a titanium oxide layer having a thickness of 2 to 20 μm under the coating, and an oxygen phase having an oxygen concentration higher than that of the base material and having a thickness of 20 to 200 μm below the titanium oxide layer. It has an enriched layer.

  Hereinafter, this invention processing member is demonstrated.

  In FIG. 2, the layer structure (surface layer structure) of the surface layer cross section of this invention is shown. As shown in FIG. 2, from the side in contact with a low melting point molten metal such as aluminum, the titanium oxide layer 5, the oxygen-enriched layer 6 composed of an α phase having a higher oxygen concentration than the base material, and the base material titanium 7 It is a surface layer structure.

  In FIG. 3, the structure (surface layer structure) of the surface layer cross section of this invention is shown. As shown in FIG. 3, corresponding to the surface layer structure shown in FIG. 2, the structure of the titanium oxide layer 5, the structure of the oxygen-enriched layer 6 composed of an α phase having a higher oxygen concentration than the substrate, and the substrate titanium The structure of the surface layer cross section can be identified from the structure of 7.

  The surface layer structure shown in FIG. 2 and the surface layer structure shown in FIG. 3 can be formed by heating (heat treatment) the base material titanium in an oxidizing atmosphere such as air at a required temperature for a required time ( This point will be described later).

The titanium oxide layer mainly consists TiO ₂ (titanium dioxide), in addition to TiO _2, TiO, even Ti ₂ O _3, the valence of titanium such as Ti ₂ O ₅ is include different titanium oxide Good.

  The thickness of the titanium oxide layer is set to 2 to 20 μm in order to ensure resistance to melting. If the thickness of the titanium oxide layer is less than 2 μm, the titanium oxide layer may be damaged or damaged when it is rubbed with peripheral equipment (for example, a jig or tool) of an apparatus for handling or processing a low melting point molten metal. The thickness of the titanium oxide layer is 2 μm or more. Preferably it is 5 micrometers or more.

  On the other hand, if the thickness of the titanium oxide layer is greater than 20 μm, the titanium oxide layer may be peeled off during handling or processing of the low melting point molten metal, so the thickness of the titanium oxide layer is set to 20 μm or less. Preferably it is 15 micrometers or less.

Even if the treatment member repeats thermal expansion and contraction, the occurrence of cracks in the surface layer portion is significantly suppressed by the surface layer structure and surface layer structure of the base titanium. This is because (a) the titanium oxide layer hardly reacts with a low melting point molten metal such as aluminum, and (b) the titanium oxide layer, an oxygen-enriched layer composed of an α phase having a higher oxygen concentration than the substrate, and This is because the thermal expansion coefficient of the base titanium is smaller than that of cast iron or TiAl ₃ and is close to each other.

  The oxygen-enriched layer is titanium or a titanium alloy in which oxygen is dissolved, and exists between the titanium oxide layer and the base titanium, and functions as a buffer layer against thermal expansion / contraction. Suppresses the occurrence of cracks.

  The base titanium is heat-treated in an oxidizing atmosphere such as air to form a titanium oxide layer on the surface layer of the base titanium and an oxide-enriched layer composed of an α phase having a higher oxygen concentration than the base. In this case, the thickness of the oxidation-enriched layer is 20 to 200 μm.

  If the thickness of the oxide-enriched layer is less than 20 μm, the thickness of the titanium oxide layer formed thereon may not reach 2 μm. Therefore, the thickness of the oxide-enriched layer is set to 20 μm or more. Preferably it is 30 micrometers or more.

  On the other hand, if the thickness of the oxide-enriched layer exceeds 200 μm, the thickness of the titanium oxide layer may exceed 20 μm. Therefore, the thickness of the oxygen-enriched layer is set to 200 μm or less. Preferably it is 150 micrometers or less.

  If the thickness of the titanium oxide layer is 5 to 15 μm and the thickness of the oxygen-enriched layer composed of an α phase having a higher oxygen concentration than that of the base material is 30 to 150 μm, the titanium oxide layer is stably oxygenated. Since it adheres to the enriched layer and hardly peels off, the occurrence of cracks is more significantly suppressed.

  The conditions for heat-treating the base titanium in an oxidizing atmosphere such as air are preferably heating temperature: 750 ° C. or higher and lower than 1000 ° C., heating time: 30 minutes or longer and 300 minutes or shorter. When the heating temperature is less than 750 ° C., it is difficult to efficiently form the titanium oxide layer and the oxygen-enriched layer therebelow, so the heating temperature is preferably 750 ° C. or higher. More preferably, it is 800 degreeC or more.

  When the heating temperature is 1000 ° C. or higher, the base material titanium is deformed during heating. Therefore, the heating temperature is preferably less than 1000 ° C. in order to suppress deformation. More preferably, it is 900 degrees C or less.

  The heating time is set in consideration of the heating temperature in order to form a titanium oxide layer and an oxygen-enriched layer having a required thickness. From the viewpoint of heat treatment efficiency, it is preferably 30 to 300 minutes, more preferably 50 to 180 minutes.

  In FIG. 4, another layer structure (surface layer structure) of the surface layer cross section of this invention is shown. In the surface layer structure shown in FIG. 4, a predetermined coating layer 8 is formed on the surface of the titanium oxide layer 5 having the surface structure shown in FIG.

From the surface side in contact with a low-melting-point molten metal such as aluminum, a coating layer 8 composed of one or more of TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE ₂ O ₃ , BN, titanium oxide layer 5 The oxygen-enriched layer 6 made of an α phase having a higher oxygen concentration than the base material and the surface layer structure made of the base material titanium.

In the layer structure shown in FIG. 4, the base titanium is heat-treated in an oxidizing atmosphere such as air to form the surface layer structure shown in FIG. 2, and then TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE _{2 is formed.} It can be formed by applying and drying a coating agent comprising one or more of O ₃ and BN. Note that RE ₂ O ₃ is an oxide of rare earth elements such as Y, La, and Lu, and may be an oxide of a mixture of rare earth elements (Misch metal).

  FIG. 5 shows another structure (surface layer structure) of the surface layer cross section of the present invention. In the structure shown in FIG. 5, the structure of each layer can be identified corresponding to the layer structure shown in FIG.

  In the surface layer structure shown in FIG. 5, it can be seen that no gap is observed between the coating layer 8 and the titanium oxide layer 5 previously formed on the surface of the titanium substrate, and the adhesion between both layers is high. That is, in the treated member of the present invention, the coating layer and the titanium oxide layer have high adhesion, are difficult to peel off, and are stable against a low melting point molten metal such as aluminum. Further improve.

  In the processing member of the present invention, the cross-sectional hardness of the oxygen-enriched layer having a thickness of 20 to 200 μm composed of an α phase having a higher oxygen concentration than the base material is continuous from the surface side of the base material toward the internal base material titanium. It is preferable to have a hardness distribution that decreases with time.

  The fact that the cross-sectional hardness of the oxygen-enriched layer under the titanium oxide layer has the above hardness distribution means that the component composition and mechanical properties change continuously from the surface side of the base material toward the internal base material titanium. This confirms that the interfacial strength between the layers is excellent. Therefore, when the cross-sectional hardness of the oxygen-enriched layer under the titanium oxide layer has the above-mentioned hardness distribution, it is possible to improve the resistance against cracking and the peel resistance in the titanium oxide layer and the coating layer.

  In FIG. 6, the hardness distribution in the cross section of the surface layer part of this invention is shown. It is the hardness distribution from the surface of the Vickers hardness measured by load 25gf in the cross section of the surface layer part of this invention processing member to the depth direction. From FIG. 6, an oxygen-enriched layer composed of an α phase having a thickness of about 70 μm and a high oxygen concentration is formed, and the hardness increases as the surface side increases and the depth from the surface increases. It turns out that it falls continuously.

  Since the oxygen-enriched layer is formed by heat-treating the base material titanium in an oxidizing atmosphere such as air, FIG. 6 suggests that the side with higher cross-sectional hardness has a higher oxygen concentration.

  The temperature of molten aluminum is 650 to 700 ° C., and the low melting point molten metal processing member is repeatedly exposed to a high temperature environment. Therefore, in order to reduce the weight of the processing member and suppress deformation, it is preferable to use titanium or a titanium alloy having a 0.2% proof stress at 500 ° C. of 75 MPa or more as the base material.

  For example, immersion in molten aluminum and pulling up to the atmosphere are repeated, and the temperature inside the ladle does not always reach 650 to 700 ° C. Therefore, based on this, a standard for defining the strength of the base material The temperature was 500 ° C.

  The yield strength of the base material was set to 75 MPa or more, which is 20% or more higher than the 0.2% yield strength at 500 ° C. of two types of industrially pure titanium (JIS H4600). This makes it possible to reduce the weight by about 20% compared to using two types of industrial pure titanium. More preferably, it is 120 MPa or more, which is about 100% or more higher.

  Titanium used as a substrate contains Cu: 0.5 to 1.5 mass%, Sn: 1.5 mass% or less, Si: 0.6 mass% or less, and the total amount of Cu and Sn is 0. It is preferable that titanium is 0.5 to 2.7% by mass with the balance being Ti and inevitable impurities. Cu: 0.5% by mass or more, 0.2% proof stress at 500 ° C .: 75 MPa or more can be secured.

  The treated member is manufactured by cold pressing or bending, but the most general industrial pure titanium (JIS H4600) has an elongation of 23% or more in the room temperature tensile test, and the base titanium is also of this level. Therefore, it is considered that the moldability is good and the processing at the processing manufacturer becomes easy.

  Therefore, in order to ensure the elongation of the room temperature tensile test of 23% or more in the base titanium, the base titanium is Cu: 1.5% by mass or less, Sn: 1.5% by mass or less, Si: 0.6% by mass %, And the total amount of Cu and Sn: 2.7% by mass or less is preferable.

  Furthermore, in order to stably secure a 0.2% proof stress at 500 ° C. of 120 MPa or more, the base material titanium is Cu: 0.5 to 1.5% by mass, Sn: 0.5 to 1.5% by mass, Si: more than 0.1 to 0.6% by mass, and the total amount of Cu and Sn: 1.0 to 2.7% is preferable.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on these one example conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

Example 1
Table 1 shows the component composition (mass%) of the base titanium, the 0.2% yield strength (MPa) at 500 ° C., and the elongation (%) during a tensile test at room temperature. These titanium substrates are subjected to hot forging and hot rolling on an ingot of a predetermined component composition manufactured by vacuum arc melting, and then annealed at 750 ° C. for 30 minutes, and then a 40 mm × 40 mm plate The surface is finished by # 600 polishing.

  Samples taken from the base titanium shown in Table 1 and subjected to the heat treatment shown in Table 2, and further, test pieces coated with the coating agent shown in Table 3 are subjected to the exposure test A described later to evaluate the resistance to melting. did.

[Exposure test A]
The test piece was immersed in molten aluminum for 8 hours, and after the immersion, the process of pulling up into the atmosphere was set as one cycle, and three cycles were performed. The molten aluminum was set to about 700 ° C. In addition, ADC12 (Al-Si-Cu type | system | group) of JISH5302 which is the most general-purpose die casting aluminum alloy was used for molten aluminum.

  The surface layer cross section of the test piece for which the exposure test A was completed was embedded in a resin, polished, and etched to prepare an observation sample. The thickness of the reaction layer with molten aluminum (maximum) and the presence / absence of cracks were evaluated in order to observe the length of about 10 mm of the observation sample with an optical microscope and to grasp the degree of resistance to erosion. About the test piece which formed the coating layer with the coating agent, the presence or absence of peeling of a coating layer was evaluated.

  Table 2 shows the thickness (maximum) of the reaction layer and the presence or absence of cracks. Comparative example no. 1, 3, 14, and 20, and Comparative Example No. 1 with a titanium oxide layer of less than 1 μm, which is the observation limit of an optical microscope, even when heat-treated in the air. In 4, 15, and 21, the reaction layer with molten aluminum was as thick as 500 μm or more, and many cracks were observed in the layer.

  Comparative Example No. 1 was heated at 1000 ° C. in the atmosphere to form a 30 μm titanium oxide layer. In No. 13, local peeling of the titanium oxide layer was observed, and a convex reaction layer having a maximum thickness of about 500 μm was observed.

  In contrast, a heat treatment in the atmosphere formed a titanium oxide layer, an oxygen-enriched layer composed of an α phase having a higher oxygen concentration than the substrate, and a surface layer structure of the substrate titanium from the surface side of the substrate. Invention Example No. In 2, 5 to 12, 16 to 19, and 22 to 39, the thickness of the titanium oxide layer and the oxygen-enriched layer is 2 to 20 μm and 20 to 200 μm, respectively, and the thickness of the reaction layer with molten aluminum Is suppressed to 20 μm or less (1/25 or less of the above-mentioned maximum thickness of 500 μm), and high melt resistance is obtained.

However, Invention Example No. In No. 12, the thickness of the titanium oxide layer is 17 μm, and the thickness of the oxygen-enriched layer therebelow is slightly thick, 126 μm. Therefore, a crack is generated in a part of the titanium oxide layer, and there is one crack in the reaction layer. Occurred. Therefore, it is understood that the preferable thickness of the titanium oxide layer and the preferable thickness of the oxygen-enriched layer are 2 to 10 μm and 20 to 100 μm, respectively. Note that the invention examples was heat-treated in the atmosphere, the analysis of the surface of the substrate titanium X-ray diffraction to detect the diffraction peak of TiO ₂ (titanium dioxide).

  Next, examples in which various coating layers are formed on a test piece will be described.

Table 3 shows the mass ratio (%) of the TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE ₂ O ₃ , and BN powders mixed in the coating agent. One or two or more powders of TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE ₂ O ₃ , BN, a water-soluble acrylic acid dispersant, and a coating agent mixed with water are applied to the test piece. And dried at about 300 ° C. These powder materials also contain components that are inevitably mixed.

  Here, a water-soluble acrylic dispersant is used, but the dispersant is not limited to the water-soluble acrylic. The powder raw material used was a fine powder having a particle size of submicron order.

  The coating agent shown in Table 3 was applied to the test piece shown in Table 2, dried, and subjected to the exposure test A. About the test piece for which the exposure test A was completed, the thickness (maximum) of the reaction layer with molten aluminum and the presence or absence of peeling of the coating layer were observed.

  Table 4 shows the level of the test piece (No in Table 2 and coating layer), the thickness (maximum) of the reaction layer with molten aluminum, and the presence or absence of peeling of the coating layer.

  By heat treatment in the atmosphere, a titanium oxide layer, an oxygen-enriched layer consisting of an α phase with a higher oxygen concentration than the substrate, and a surface layer structure of the substrate titanium are formed from the surface side, and further required on the titanium oxide layer Invention Example No. having a coating layer of In 51, 53 to 65, and 67 to 92, the thickness of the reaction layer is as thin as less than 1 μm, which is the observation limit of the optical microscope (the reaction layer is hardly formed), there is no peeling of the coating layer, and the resistance to melting The property is extremely excellent.

  On the other hand, Comparative Example No. 1 in which a coating layer was formed on titanium as a base material. In 52 and 66, since the difference in thermal expansion / contraction between the base titanium and the coating layer is large, peeling occurs in the coating layer, and a reaction layer of the base and molten aluminum is formed.

  As can be seen from the results of the exposure test A shown in Table 2 and Table 4, the symbols A03 and B01-17 of the base material having a 0.2% proof stress of 75 MPa or more at 500 ° C. shown in Table 1, and at room temperature Even with the symbols B01 to 03, B05, B06, B08, B09, and B11 to 15 having an elongation of 23% or more, the same effect as the effect of the surface layer structure of the processing member of the present invention is obtained.

(Example 2)
Next, Table 5 shows the reaction layer with “solder” and the presence or absence of cracks as a result of the following exposure test B.

[Exposure test B]
The test piece was immersed in molten Sn—Pd-based solder (60% Sn-40% Pd) for 8 hours, and after the immersion, the process of pulling it up to the atmosphere was performed as 6 cycles. The temperature of the molten solder was about 200 ° C.

  The surface layer cross section of the test piece for which the exposure test B was completed was embedded in a resin observation table, polished, and etched to prepare an observation sample. About 10 mm length of the observation sample was observed with an optical microscope, and the thickness (maximum) of the reaction layer produced by reacting with “solder” and the presence / absence of cracks were evaluated in order to grasp the degree of resistance to melting.

  Invention Example No. 1 in which a surface structure of titanium oxide layer, oxygen-enriched layer composed of α phase having higher oxygen concentration than the base material, and surface layer structure of base material titanium was formed from the surface side by heat treatment in the atmosphere. In 102, 105, and 119, the thickness of the reaction layer is 2 μm or less, which is very less than one tenth of the thickness of the reaction layer (28 μm and 27 μm) in Comparative Examples 101, 103, and 117 as they are as the base material. It is small and has excellent resistance to melting against "solder".

  As shown in FIG. 7, a thick reaction layer 10 is formed between the solder (Sn—Pb system) 9 and the base material titanium 11 as it is.

  Invention Example No. with a coating layer formed In 106 to 116 and 120 to 126, the thickness of the reaction layer is as thin as less than 1 μm, which is the observation limit of the optical microscope (the reaction layer is hardly formed), and it has excellent resistance to melting against “solder”. Showing sex. In the exposure test B, since the temperature of the “solder” was as low as about 200 ° C., no crack was observed in the reaction layer.

  As described above, according to the present invention, it is possible to provide a low-melting point molten metal-treated member that is made of titanium and has excellent resistance to melting against low-melting point molten metals such as low-melting aluminum. The low-melting-point molten metal processing member of the present invention is lightweight and excellent in durability, such as an aluminum casting, a ladle for pumping a low-melting-point molten metal and conveying it to a mold or a die-cast machine, or a molten metal It can be used as a processing member such as oysters to remove the “flour” floating on the surface of the pond.

  And if the low melting-point molten metal processing member of this invention is used, molten metal heat retention property will increase and work efficiency will improve. Therefore, the industrial contribution of the present invention is extremely remarkable.

1 molten aluminum solidified layer 2 of titanium and aluminum intermetallic alloy (TiAl ₃₎ layer 3 substrate titanium 4 crack 5 oxygen concentration than the titanium oxide layer 6 The substrate is made of a high α-phase oxygen enriched layer 7 Substrate Titanium 8 Coating layer 9 Solder (Sn-Pb series)
10 Reaction layer of base material titanium and “solder” 11 Base material titanium

Claims (6)

  The substrate is made of titanium, has a titanium oxide layer with a thickness of 2 to 20 μm on the surface of the substrate, and has an α phase having an oxygen concentration higher than that of the substrate under the titanium oxide layer. A low-melting-point molten metal-treated member having excellent melting resistance, characterized by having an oxygen-enriched layer of ~ 200 µm. The substrate is made of titanium, and has a coating layer made of one or more of TiO ₂ , MgO, SiO ₂ , Al ₂ O ₃ , RE ₂ O ₃ , and BN on the outermost surface of the substrate, A titanium oxide layer having a thickness of 2 to 20 μm is formed under the coating layer, and an oxygen enrichment having a thickness of 20 to 200 μm is formed under the titanium oxide layer and consisting of an α phase having a higher oxygen concentration than the base material. A low-melting-point molten metal-treated member having excellent melt resistance, comprising a layer.   2. The titanium oxide layer and the oxygen-enriched layer are formed by heating a base material in an oxidizing atmosphere at 750 ° C. or higher and lower than 1000 ° C. for 30 minutes or longer and 300 minutes or shorter. Or the low melting-point molten metal processing member which is excellent in the melt resistance as described in 2.   4. The melt resistance according to claim 1, wherein the cross-sectional hardness of the oxygen-enriched layer forms a hardness distribution that continuously decreases from the surface side to the inside of the substrate. A processing member for low melting point molten metal with excellent damage properties.   The low melting point metal excellent in melting resistance according to any one of claims 1 to 4, wherein 0.2% proof stress at 500 ° C of titanium used as the base material is 75 MPa or more. Processing member.   Titanium used as the base material contains Cu: 0.5 to 1.5 mass%, Sn: 1.5 mass% or less, Si: 0.6 mass% or less, and the total amount of Cu and Sn is The processing member for low melting point metal having excellent melt resistance according to any one of claims 1 to 5, wherein 0.5 to 2.7% by mass, and the balance is made of Ti and inevitable impurities. .