Patent Publication Number: US-2018037978-A1

Title: High temperature wear-resistant aluminum-bronze-based material

Description:
TECHNICAL FIELD 
     The present invention relates to an aluminum-bronze-based material having high wear resistance in high-temperature environments. 
     BACKGROUND ART 
     In high-temperature environments in industrial machines and facilities such as incinerators, copper alloys such as high-strength brass castings are generally used in sliding members such as exhaust valve bushes. 
     As an example of such a sliding member, Patent Literature 1 discloses a copper-based bearing sliding material which contains 3 to 15% by mass of Al, 1 to 8% by mass of Mn, 0.05 to 5% by mass of Si, 0.5 to 5% by mass of Ni, and 1 to 10% by mass of Fe, with the remainder being unavoidable impurities and Cu, in which an Fe—Mn—Si-based hard material is dispersed. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP3929288B 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, the hardness of the matrix material of the known aluminum bronze-based sliding member as disclosed in Patent Literature 1 decreases in high-temperature environments (for example, a high-temperature environment at 150° C. to 350° C.). Accordingly, the allowable surface pressure value is lowered, and it cannot be said that wear resistance is sufficient. Thus, a further sophisticated material is demanded to be supplied in order to reduce the replacement frequency of sliding members in industrial machines which are used in adverse environments where the replacement is not easy. 
     The present invention has been made to solve such a known problem, and an object thereof is to provide a material which has both surface pressure resistance and wear resistance not only in normal temperature environments but also in high-temperature environments. 
     Solution to Problem 
     The high temperature wear-resistant aluminum-bronze-based material according to the present invention is characterized in that an Al content is 9.0% by mass or more and 11.0% by mass or less, an Ni content is 1.0% by mass or more and 3.0% by mass or less, an Mn content is 8.5% by mass or more and 15.0% by mass or less, an Si content is 2.0% by mass or more and 4.0% by mass or less, an Fe content is 0.5% by mass or more and 5.0% by mass or less, and a Co content is 0.01% by mass or more and 1.5% by mass or less, with the remainder being substantially Cu. 
     Advantageous Effects of Invention 
     According to the high temperature wear-resistant aluminum-bronze-based material according to the present invention, there can be provided a sliding member which has both surface pressure resistance and wear resistance even in high-temperature environments. The reduction of the wear amount due to sliding movements enables the replacement frequency of a component such as a sliding member to be drastically reduced in industrial machines and molds of which sliding members are not easy to replace. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a plate-like sliding member which adopts as a base material a high temperature wear-resistant aluminum-bronze-based material according to the present embodiment and which is the type having no solid lubricant. 
         FIG. 2  is a schematic diagram of a plate-like sliding member which adopts as a base material the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment and which is the type having a solid lubricant. 
         FIG. 3  is a schematic diagram of a hollow cylindrical sliding member which adopts as a base material a high temperature wear-resistant aluminum-bronze-based material according to the present embodiment and which is the type having no solid lubricant. 
         FIG. 4  is a schematic diagram of a hollow cylindrical sliding member which adopts as a base material a high temperature wear-resistant aluminum-bronze-based material according to the present embodiment and which is the type having a solid lubricant. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a high temperature wear-resistant aluminum-bronze-based material according to an embodiment of the present invention will be described in detail. 
     The high temperature wear-resistant aluminum-bronze-based material according to the present embodiment is a material which contains Al, Ni, Mn, Si, Fe, and Co in respective predetermined amounts in terms of % by mass, with the remainder being Cu. 
     The high temperature wear-resistant aluminum-bronze-based material according to the present embodiment has an Al content of 9.0% by mass or more and 11.0% by mass or less, and preferably 9.0% by mass or more and 10.0% by mass or less. When the Al content is within the above-described value range, the matrix material can have an appropriate hardness of HV280 or more, thereby improving surface pressure resistance. It is noted that the hardness of the matrix material is measured by a method in accordance with JIS 22243 2008. 
     When the Al content is less than the above-described value range, hardness becomes insufficient. On the other hand, when the Al content exceeds the above-described value range, hardness becomes high, but toughness becomes low. Therefore, heat resistance is reduced. 
     Also, the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment has an Ni content of 1.0% by mass or more and 3.0% by mass or less, and preferably 1.5% by mass or more and 2.5% by mass or less. The inclusion of Ni enables the solubility limit of Al in an a phase to be widened, and also the melting point of the matrix material to be increased thereby improving heat resistance. Furthermore, the inclusion of Ni contributes to deposition of a hard material, together with Fe—Si—Mn described later. 
     When the Ni content is less than the above-described value range, the heat resistance of the matrix material is not satisfied. On the other hand, when the Ni content exceeds the above-described value range, there is the drawback that the matrix material is embrittled, and a manufactured product becomes expensive because Ni is a rare metal. 
     Also, when the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment hasastructureinwhichanFe—Mn—Si-basedhardmaterialisdispersed, the wear resistance as a sliding member improves. 
     The high temperature wear-resistant aluminum-bronze-based material according to the present embodiment has an Mn content of 8.5% by mass or more and 15.0% by mass or less, preferably 8.5% by mass or more and 13.0% by mass or less, and more preferably 8.5% by mass or more and 10.0% by mass or less. When the Mn content is within the above-described value range, Mn, together with Si, Mn and the like described later, causes an Fe—Si—Mn-based hard material to be deposited in the matrix material, thereby improving wear resistance. Also, when the Mn content ratio is increased, the matrix material can have suitable toughness. 
     When the Mn content is less than the above-described value range, toughness which is necessary and sufficient as the matrix material cannot be obtained. When the Mn content exceeds the above-described value range, toughness becomes more than necessary. 
     Also, the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment has an Fe content of 0.5% by mass or more and 5.0% by mass or less, preferably 1.0% by mass or more and 5.0% by mass or less, and more preferably 1.5% by mass or more and 5.0% by mass or less. When the Fe content is within the above-described value range, Fe is deposited together with Mn—Si and the like as a hard material in the matrix material, and particularly contributes to a finer structure of the above-described hard material, thereby improving the properties as a sliding member. 
     When the Fe content exceeds the above-described value range, corrosion resistance is reduced. Furthermore, Fe is dissolved to the degree that is the solubility limit (peritecteutectic point) or more thereby to be segregated in the structure, which leads to the increase of a friction coefficient. Therefore, aggression toward a mating material is increased. In consideration of the fact in which a mating material of sliding movements is mainly a steel material, excessive inclusion of Fe is likely to cause adhesion, which leads to reduced sliding properties. 
     Also, the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment has an Si content of 2.0% by mass or more and 4.0% by mass or less, preferably 2.0% by mass or more and 3.0% by mass or less, and more preferably 2.5% by mass or more and 3.0% by mass or less. When the Si content is within the above-described value range, Si, together with Mn and Fe, causes a eutectic hard material to be deposited, thereby improving sliding properties. 
     Also, the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment has a Co content of 0.01% by mass or more and 1.5% by mass or less. According to the present embodiment, the inclusion of Co improves heat resistance. 
       FIGS. 1 to 4  are each a diagram illustrating a configuration of a sliding member which adopts as a base material the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment.  FIG. 1  illustrates a plate-like sliding member  1  which is the type having no solid lubricant.  FIG. 2  illustrates a plate-like sliding member  2  which is the type having a plurality of pieces of a solid lubricant  3  embedded therein.  FIG. 3  illustrates a hollow cylindrical sliding member  4  which is the type having no solid lubricant.  FIG. 4  illustrates a hollow cylindrical sliding member  5  which is the type having a plurality of pieces of a solid lubricant  6  embedded therein. It is noted that  FIGS. 1 to 4  illustrate examples of the form of a sliding member, and the form of the sliding member is not limited to these embodiments. 
     As illustrated in the drawings, a plurality of pieces of a solid lubricant having a self-lubricating action may be embedded in portions of a sliding surface formed from the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment. Examples of the solid lubricant according to the present embodiment to be used may include solid lubricants, such as a graphite-based solid lubricant, a PTFE-based solid lubricant, a MoS2-based solid lubricant, and a Pb alloy-based solid lubricant. 
     According to the present embodiment, the provision of the sliding surface in which a solid lubricant is embedded causes the lubricant to be dispersed on the sliding surface even in high-temperature environments. Therefore, the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment can have improved sliding properties, and becomes suitable as a sliding member. 
     Also, it is preferable that the high temperature wear-resistant aluminum-bronze-based material according to the present embodiment have a Vickers hardness of HV280 or more, an elongation of 0.5% or more, and a tensile strength of 500 N/mm 2  or more. When the hardness is equal to or more than HV280, surface pressure resistance and wear resistance in high-temperature environments are improved. 
     Also, when the elongation is equal to or more than 0.5%, there can be obtained the material strength which is suitable for a sliding member. It is noted that as described herein, the “elongation” refers to an elongation that is measured with a tensile test piece in accordance with JIS 22241. Also, when the tensile strength is equal to or more than 500 N/mm 2  or more, load bearing properties in high-temperature environments are improved. The sliding properties of the present invention will be described in detail by way of examples. 
     EXAMPLES 
     Hereinafter, examples of the present invention will be described. It is noted that the present invention is not limited to the following examples. 
     A plurality of copper alloys of the composition as illustrated in Table 1 were melted in a high-frequency furnace and cast with a mold, thereby to prepare a block test piece according to each of Examples 1 to 8 and Comparative Examples 1 to 5. Table 1 indicates composition values [Wt %] of the test pieces according to Examples 1 to 8 and Comparative Examples 1 to 5. The composition values were obtained by ICP emission spectrochemical analysis. 
     As illustrated in Table 1, the test pieces according to Example 1 to Example 8 have a composition in which an Al content was 9.0% by mass or more and 11.0% by mass or less, an Mn content was 8.5% by mass or more and 15.0% by mass or less, an Fe content was 0.5% by mass or more and 5.0% by mass or less, an Ni content was 1.0% by mass or more and 3.0% by mass or less, an Si content was 2.0% by mass or more and 4.0% by mass or less, and a Co content was 0.01% by mass or more and 1.5% by mass or less, with the remainder being substantially Cu. 
     On the other hand, the composition of part of the metals contained in each of Comparative Example 1 to Comparative Example 5 is outside the range of the above-described examples. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Cu 
                 Al 
                 Ni 
                 Mn 
                 Si 
                 Fe 
                 Co 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 Remainder 
                 9.37 
                 1.87 
                 14.80 
                 2.86 
                 4.90 
                 1.00 
               
               
                 Example 2 
                 Remainder 
                 9.22 
                 2.01 
                 8.73 
                 2.95 
                 1.68 
                 1.06 
               
               
                 Example 3 
                 Remainder 
                 9.38 
                 1.73 
                 9.06 
                 3.32 
                 1.16 
                 0.27 
               
               
                 Example 4 
                 Remainder 
                 9.33 
                 1.97 
                 14.30 
                 2.86 
                 1.67 
                 1.02 
               
               
                 Example 5 
                 Remainder 
                 9.23 
                 1.98 
                 8.55 
                 2.35 
                 1.59 
                 0.27 
               
               
                 Example 6 
                 Remainder 
                 9.66 
                 1.97 
                 10.90 
                 2.87 
                 1.62 
                 1.00 
               
               
                 Example 7 
                 Remainder 
                 9.24 
                 1.91 
                 8.84 
                 2.87 
                 4.75 
                 1.06 
               
               
                 Example 8 
                 Remainder 
                 9.34 
                 2.03 
                 10.80 
                 2.95 
                 4.99 
                 0.047 
               
               
                 Comparative 
                 Remainder 
                 4.74 
                 2.05 
                 4.17 
                 2.69 
                 5.10 
                 1.05 
               
               
                 Example 1 
               
               
                 Comparative 
                 Remainder 
                 8.63 
                 0.87 
                 10.26 
                 1.09 
                 2.89 
                 0.28 
               
               
                 Example 2 
               
               
                 Comparative 
                 Remainder 
                 9.20 
                 0.78 
                 10.35 
                 3.26 
                 0.86 
                 0.27 
               
               
                 Example 3 
               
               
                 Comparative 
                 Remainder 
                 9.44 
                 0.82 
                 4.80 
                 3.15 
                 1.01 
                 0.28 
               
               
                 Example 4 
               
               
                 Comparative 
                 Remainder 
                 9.46 
                 0.97 
                 4.54 
                 3.17 
                 1.95 
                 0.37 
               
               
                 Example 5 
               
               
                   
               
            
           
         
       
     
     Table 2 indicates measurement results of the hardness and wear amount for the block test pieces according to Examples 1 to 8 and Comparative Examples 1 to 5. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Hardness 
                 Wear amount 
               
               
                   
                 [HV] 
                 [μm] 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Example 1 
                 372 
                 42.8 
               
               
                   
                 Example 2 
                 341 
                 42.5 
               
               
                   
                 Example 3 
                 334 
                 42.3 
               
               
                   
                 Example 4 
                 362 
                 40.8 
               
               
                   
                 Example 5 
                 302 
                 40.5 
               
               
                   
                 Example 6 
                 306 
                 36.5 
               
               
                   
                 Example 7 
                 342 
                 35.5 
               
               
                   
                 Example 8 
                 289 
                 35.5 
               
               
                   
                 Comparative Example 1 
                 181 
                 48.0 
               
               
                   
                 Comparative Example 2 
                 321 
                 53.8 
               
               
                   
                 Comparative Example 3 
                 334 
                 51.5 
               
               
                   
                 Comparative Example 4 
                 297 
                 58.8 
               
               
                   
                 Comparative Example 5 
                 410 
                 49.8 
               
               
                   
                   
               
            
           
         
       
     
     The hardness was obtained by measuring the Vickers hardness of the block test pieces according to Examples 1 to 8 and Comparative Examples 1 to 5 at room temperature. As understood from Table 2, the hardness of the test pieces according to Examples 1 to 8 is 280 or more. 
     The wear amount was measured by performing a block-on-ring type sliding test for the block test pieces according to Examples 1 to 8 and Comparative Examples 1 to 5. The condition of the sliding test is a surface pressure of 10 MPa, a sliding speed of 10 m/min, an environment temperature of 250° C., and a sliding distance of 500 m. The sliding test was performed with a dedicated test machine. The block test piece was pressed against a ring test piece in a state where the temperature in the test machine was maintained at 250° C. thereby to apply a load, and the ring test piece was rotated at a constant speed. It is noted that S45C (quenched and tempered at high frequency) was used as the ring test piece that is a mating material. 
     As understood from Table 2, the wear amount of the block test pieces according to Examples 1 to 8 is 35.5 μm or more and 42.8 μm or less, indicating that the wear amount is small. On the other hand, the wear amount of the block test pieces according to Comparative Examples 1 to 5 is 48.0 μm or more and 58.8 μm or less, indicating that the wear amount is large. Thus, the effects of the examples of the present invention were confirmed. 
     In particular, the wear amount is 40.8 μm or less in Example 4 to Example 8. Therefore, it is understood that these compositions are preferable. Furthermore, the wear amount is 36.5 μm or less in Example 6 to Example 8. Therefore, it is understood that these compositions are more preferable. 
     As described above, according to the high temperature wear-resistant aluminum-bronze-based material of the present invention, there can be provided a sliding member which has both surface pressure resistance and wear resistance even in high-temperature environments. Furthermore, by reducing the wear amount of the sliding member, the replacement frequency of the sliding member can be drastically reduced in industrial machines of which the sliding members are not easy to replace.