JP5835456B2 - Friction material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a means for arbitrarily controlling the rotation or movement of various machines such as machine tools, construction machines, agricultural machines, automobiles, two-wheeled vehicles, railways, aircrafts and ships, so-called friction materials used for clutches or brakes. is there.

  A friction material having a high coefficient of friction is demanded in order to reduce the size and weight of clutches and brakes. As a friction material having a high friction coefficient, a friction material containing copper and nickel as metal components is known. As the prior art, there is a friction material composition containing 10% to 70% Ni and 30% to 80% Cu by weight% in the matrix (for example, see Patent Document 1).

JP 63-30617 A

  A friction material used for a clutch or a brake is manufactured by sintering a mixture of a metal powder and a friction modifier powder. In recent years, the Chemical Substance Emission Control Management Promotion Law (hereinafter referred to as the PRTR Law) has been enacted for the purpose of environmental protection, and nickel, chromium, lead, vanadium compounds, manganese, and so Molybdenum is now included in the Class 1 Designated Chemical Substances after the 2008 revision of the PRTR Law.

  Since the first-class designated chemical substance is a management target of the PRTR method, a friction material that does not use the first-class designated chemical substance in the PRTR method as a raw material powder is desirable from the viewpoint of management cost and environmental load. In addition, discussions have been made to add copper contained in the friction material of motorcycles to the subject of regulation.

  The present invention uses a raw material powder that has a low environmental load from the background as described above, and is equivalent to or more than a friction material obtained by using a conventional metal such as nickel or copper as a raw material powder. An object of the present invention is to provide a friction material having a high friction coefficient.

The gist of the present invention is as follows.
(1) A friction material in which a friction modifier is contained in a metal phase containing Fe and Si, and in the metal phase, Fe element is contained in an amount of 70 to 98% by mass with respect to the entire metal phase, A friction material that is contained in an amount of 2 to 30% by mass with respect to the entire metal phase (however, the total content of Fe element and Si element is 100% by mass or less).

  (2) The content of the metal phase is 55 to 70 mass% with respect to the entire friction material, and the content of the friction modifier is 30 to 45 mass% with respect to the entire friction material, The friction material according to (1), wherein the total content of the metal phase and the friction modifier is 100% by mass.

  (3) The content of Fe element in the metal phase is 70 to 98% by mass, the content of Si element in the metal phase is 2 to 30% by mass, and the total content of Fe element and Si element is The friction material according to (1) or (2), which is 100% by mass.

  (4) In any one of (1) to (3), the metal phase contains 15% by mass or less of P element with respect to the entire metal phase in place of part of the Fe element contained in the metal phase. Friction material.

  (5) The friction material according to any one of (1) to (4), wherein the friction modifier contains hard particles and a lubricating substance.

  (6) The content of the hard particles is 10 to 20% by mass with respect to the entire friction material, and the content of the lubricating substance is 20 to 28% by mass with respect to the entire friction material, The friction material according to (5), wherein the content of the friction modifier is 30 to 45 mass% with respect to the entire friction material.

  (7) The friction material according to (5) or (6), wherein the lubricating substance contains graphite and calcium fluoride.

  (8) The content of the metal phase is 58 to 68 mass% with respect to the entire friction material, and the content of the friction modifier is 32 to 42 mass% with respect to the entire friction material, The friction material according to any one of (1) to (7), wherein the total content of the metal phase and the friction modifier is 100% by mass.

  (9) Any one of (1) to (8), wherein the metal phase contains 10% by mass or less of the P element with respect to the entire metal phase in place of a part of the Fe element contained in the metal phase. Friction material.

(10) The hard particles are silica (SiO ₂ ), alumina (Al ₂ O ₃ ), magnesia (MgO), titania (TiO ₂ ), zirconia (ZrO ₂ ), yttria (Y ₂ O ₃ ), mullite (Al ₂ SiO ₅ ), zircon sand (ZrSiO ₄ ), tungsten steel (Fe—W), tungsten carbide (WC), and silicon carbide (SiC). Any friction material.

  (11) 55 to 70% by mass of metal powder containing 70 to 98% by mass of Fe and 2 to 30% by mass of Si (however, the total of the content of Fe element and the content of Si element is 100% by mass or less) ), The step 1 of mixing the friction modifier powder 30 to 45% by mass (however, the total of the metal powder and the friction modifier powder is 100% by mass), and the mixture obtained in the step 1 is sintered. A method for producing a friction material, comprising: step 2.

  (12) The friction material according to (11), wherein Fe in the metal powder is an iron-based metal powder containing 85% by mass or more of an Fe element produced by one or both of a carbonyl iron powder method and an atomization method. Production method.

  The friction material of the present invention uses a raw material powder with a low environmental load as its production raw material, and therefore has a low environmental load. Furthermore, the friction material of the present invention has a high friction coefficient equal to or higher than that of a friction material obtained by using a conventional metal such as nickel or copper as a raw material powder.

Hereinafter, the present invention will be described in detail.
The friction material of the present invention is formed by containing a friction modifier in a metal phase containing Fe and Si. The said metal phase consists of a metal which has Fe as a main component, and Fe element is contained 70-98 mass% with respect to the whole metal phase (100 mass%). Moreover, Si element is contained 2-30 mass% with respect to the whole metal phase (100 mass%).

  When the amount of Fe element contained in the metal phase is less than 70% by mass, the strength of the friction material is remarkably lowered. On the other hand, when the amount of Fe element contained in the metal phase exceeds 98% by mass, a high friction coefficient is maintained. It becomes difficult to suppress the wear amount of the friction material and the counterpart material. From the above, the amount of Fe element was set to 70 to 98% by mass. Among them, the amount of Fe element (content) is preferably 90 to 98% by mass.

  Further, if the amount of Si element contained in the metal phase is less than 2% by mass, it becomes difficult to maintain a high friction coefficient and suppress the wear amount of the friction material and the counterpart material, while the amount of Si element contained in the metal phase is small. If it exceeds 30% by mass, the strength of the friction material is significantly reduced. From the above, the amount of Si element was set to 2 to 30% by mass. Among these, it is preferable that Si element amount (content) is 2-10 mass%.

  The metal phase in the friction material of the present invention contains Fe and Si, and the total content of the Fe element and the Si element is 100% by mass or less with respect to the entire metal phase. The total is more preferably 100% by mass.

  The amount of Fe element and the amount of Si element contained in the metal phase in the friction material of the present invention can be measured by energy dispersive X-ray analysis (EDX) or wavelength dispersive X-ray analysis (WDX).

  In general, the main component of the counterpart material in contact with the friction material is often Fe element, and when the main component of the friction material is Fe element as in the present invention, the affinity between the counterpart material and the friction material is high. Therefore, adhesion tends to occur, and as a result, the wear amount of both the friction material and the counterpart material may increase.

  However, by adding Si element to the metal phase of the friction material containing Fe element as a main component, it was possible to suppress wear of the friction material and the counterpart material. This is because, by adding Si element to the metal phase of the friction material mainly composed of Fe element, an oxide film is formed on the sliding surface of the friction material that comes into contact with the counterpart material at the time of braking, and the adhesion of the same kind of component occurs. This is considered to be because the wear is reduced.

  Also, by adding a metallic Si element to the Fe element which is the main component of the metal phase in the friction material of the present invention, the friction coefficient at a high temperature can be made higher than that of a conventional friction material mainly composed of copper. It was. This is presumably because iron has a higher melting point than copper and plastic flow during braking is less likely to occur.

  Next, in the friction material of the present invention, the content of the metal phase is 55 to 70 mass% with respect to the entire friction material (100 mass%), and the content of the friction modifier is the entire friction material (100 mass%). ) To 30-45% by mass (however, the total of these contents is 100% by mass).

  When the content of the metal phase is less than 55% by mass with respect to the entire friction material, the friction coefficient and the strength are reduced, and when the content of the metal phase exceeds 70% by mass with respect to the entire friction material, it is obtained. This is because it tends to be difficult to adjust the friction characteristics. Among these, it is preferable that the content of the metal phase is 58 to 68 mass% with respect to the entire friction material, and the content of the friction modifier is 32 to 42 mass% with respect to the entire friction material (however, these The total content of is 100% by mass).

  The friction material of the present invention contains P element in an amount of 15% by mass or less with respect to the entire metal phase (100% by mass) instead of a part of Fe element contained in the metal phase constituting the friction material. Is preferred. This is because when the element P is contained, the sinterability of the raw material powder of the friction material of the present invention is improved, but when the element P is contained in an amount exceeding 15% by mass with respect to the entire metal phase, the present invention in a high temperature environment This is because the wear amount of the friction material tends to increase. Among these, it is more preferable that the metal phase contains 10% by mass or less of the P element with respect to the entire metal phase (100% by mass) instead of a part of the Fe element contained in the metal phase.

  The amount of P element contained in the metal phase can be measured by EDX or WDX. Further, although the P element is not a metal element, for example, instead of a part of the Fe element contained in the metal phase (assuming that the content of Fe element in the metal phase is 80% by mass), the P element is a metal. To be contained in an amount of 15% by mass with respect to the whole phase has the following meaning. That is, 80% by mass of 100% by mass of the entire metal phase was Fe element and the remaining 20% by mass was another element, but 65% by mass of 100% by mass of the entire metal phase was Fe element and 15% by mass. Means P element and the remaining 20% by mass is changed to the composition of other elements.

  The friction material of the present invention may contain impurities in the raw materials and impurities mixed from the manufacturing process. Examples of impurities contained as metals in the friction material of the present invention include Al elements and Mg elements. If the total amount of impurities such as Al element and Mg element contained as metal in the friction material of the present invention is 3% by mass or less with respect to the entire metal phase, it will affect the performance of the friction material of the present invention. Absent. The amount of Al element and the amount of Mg element contained in the metal phase of the present invention can be measured by EDX or WDX.

  Examples of the friction modifier contained in the friction material of the present invention include hard particles that adjust the wear resistance of the friction material, and lubricating substances that adjust the lubricity.

Specific examples of the hard particles include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), magnesia (MgO), titania (TiO ₂ ), zirconia (ZrO ₂ ), yttria (Y ₂ O ₃ ), mullite ( Al ₂ SiO ₅ ), zircon sand (ZrSiO ₄ ), tungsten steel (Fe—W), tungsten carbide (WC), silicon carbide (SiC), and the like.

Specific examples of the lubricating substance include talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), calcined talc (Mg ₃ Si ₄ O ₁₁ ), graphite (C), coke (C), calcium carbonate ( Examples include CaCO ₃ ), calcium oxide (CaO), and calcium fluoride (CaF ₂ ). Among these, graphite and calcium fluoride are preferable as the lubricating substance because the lubricity improvement effect of the friction material is good.

  About such a friction modifier, content of the said hard particle is 10-20 mass% with respect to the whole friction material (100 mass%), and content of a lubricating substance is the whole friction material (100 mass%). ) And the content of the friction modifier is 30 to 45% by mass with respect to the entire friction material (100% by mass), the friction material has wear resistance and lubricity. Since it becomes favorable, it is further preferable.

  The friction material of the present invention described above is obtained by sintering a mixture of metal powder containing Fe and Si and friction modifier powder. By sintering, the metal powder forms a metal phase, and the friction modifier powder is dispersed in the metal phase as a friction modifier. Specific examples of the method for producing the friction material of the present invention include the following methods.

  As a raw material powder of the friction material of the present invention, a metal powder containing 70 to 98 mass% Fe and 2 to 30 mass% Si (provided that the total content of Fe element and Si element in the metal powder is 100) And the friction modifier powder is prepared. If the average particle size of the metal powder and the friction modifier powder exceeds 500 μm, the moldability is reduced and it is difficult to produce a friction material, whereas if the average particle size is less than 1 μm, it is difficult to mix uniformly. Therefore, the average particle size of the metal powder and the friction modifier powder is preferably 1 to 500 μm. In the present specification, the average particle diameter of each raw material powder is measured by the Fisher method.

  About the usage-amounts of the said metal powder and friction modifier powder, it is preferable to mix 55-70 mass% of metal powder and 30-45 mass% of friction modifier powder (In addition, these total is 100 mass%. is there). This is because when the amount of metal powder used is less than 55% by mass with respect to the total mixture obtained, the metal phase decreases, the friction coefficient and strength of the friction material decrease, and the amount of metal powder used decreases with respect to the total mixture. This is because if the amount exceeds 70% by mass, the metal phase increases and it tends to be difficult to adjust the required frictional characteristics.

  Thus, the friction material of this invention can be manufactured through the process 1 which mixes the metal powder and friction modifier powder which were mix | blended in the predetermined | prescribed ratio, and the process 2 which sinters the obtained mixture. The sintering temperature in this case is usually 800 to 1200 ° C.

  In the production of the friction material of the present invention, for example, the friction material obtained in Step 3 and Step 2 of molding the mixture obtained in Step 1 into a predetermined shape is joined to the core plate using a resin or brazing material. Of course, other steps such as the step 5 of impregnating or applying the resin or the anticorrosive component to the friction material obtained in the steps 4 and 2 may be performed.

  Further, in addition to the case where the step 3 is carried out, in the case of obtaining the friction material of the present invention by molding into a predetermined shape, the raw material powder is mixed as needed to form a mixture, Pressure is applied during sintering to obtain a sintered body having a predetermined shape. In this case, the molding pressure in the pressure sintering varies greatly depending on the production process, but the range is 0.1 Pa to 980 MPa.

  As an Fe component in the metal powder used in the production of the friction material of the present invention, an iron-based metal containing 85% by mass or more of Fe element produced by one or both of the carbonyl iron powder method and the atomizing (spraying) method Use of powder is more preferable because the strength of the friction material is improved. Moreover, when the iron-based metal powder manufactured by the atomizing method is used, the strength of the molded body increases and it becomes easy to manufacture.

  Specific examples of the iron-based metal powder produced by the carbonyl iron powder method include carbonyl iron powder composed of Fe element (100% by mass). Specific examples of the iron-based metal powder produced by the atomizing method include phosphorus-containing iron powder composed of P element: 0.3 to 15% by mass and Fe element: balance. Among these, the phosphorus containing iron powder which consists of P element: 0.5-1.0 mass% and Fe element: remainder is still more preferable.

  In particular, the iron-based metal powder is composed of iron powder and phosphorus-containing iron powder composed of P element: 0.3 to 15% by mass and Fe element: balance, and the mixing ratio of iron powder and phosphorus-containing iron powder is weight. The ratio of iron powder (A): phosphorus-containing iron powder (B) = (3-9) :( 7-1) (however, the sum of (A) and (B) is 10). It is more preferable to use a mixed mixture because the moldability and sinterability are improved.

  In addition, as the Si component of the metal powder used in the production of the friction material of the present invention, a metal powder made of Si may be used, or a silicon-based metal powder made of Si and other metal elements (Si The content is usually 80% by mass or more).

  For example, as a silicon-based metal powder containing 80% by mass or more of Si element, specifically, a metal silicon powder composed of Si element, a ferrosilicon powder composed of 80% by mass or more of Si element and the balance Fe element, 80% of Si element % Of aluminum silicon and the balance Al element, and a mixture thereof.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these.

  As raw material powders used in the production of the friction material of the present invention, carbonyl iron powder (100 mass% Fe) having an average particle diameter of 4.4 μm and phosphorus-containing atomized iron powder having an average particle diameter of 60 μm (P: 0.54 to 0.00). 66% by mass, Fe: 98.89 to 99.46% by mass, balance Al), metal silicon powder having an average particle size of 40 μm (Si: 96.0% by mass, balance: Fe, Al and Mg), average particle size of 40 μm Ferrosilicon powder (Si: 80% by mass, Fe: 20% by mass), graphite powder having an average particle size of 70 μm, zircon sand powder having an average particle size of 40 μm, mullite powder having an average particle size of 30 μm, and an average as a friction modifier powder A calcium fluoride powder having a particle size of 50 μm was prepared.

Moreover, copper powder with an average particle size of 40 μm, tin powder with an average particle size of 40 μm, and nickel powder with an average particle size of 5 μm were prepared as metal powders to be used as comparative products.
In addition, the average particle diameter of each raw material powder was measured by the Fisher method.

  Next, the raw material powders described above were weighed according to the composition shown in Tables 1 and 2 below, and mixed to obtain a mixture. The resulting mixture was molded into a brake pad shape and then subjected to pressure sintering at the sintering temperature and molding pressure shown in Tables 1 and 2.

  The composition of the metal phase of the obtained friction material was measured by EDX. The results are shown in Table 3 below.

  The room temperature shear strength of the unused friction material and the friction material after the thermal shock test was measured. The shear jig and test procedure used for the shear test were in accordance with JIS D 4422 (2007). The thermal shock test is a test in which the friction material is held at 600 ° C. for 1 hour and then cooled with water three times, and the thermal shock resistance of the friction material is evaluated.

  Further, the friction characteristics of the friction material were evaluated according to a passenger car brake device dynamometer test JASO C406-82. Specifically, SUS (stainless steel) was used as the counterpart material, and a friction test was performed according to the test procedure shown in Table 5 below. In addition, P1 was selected as the vehicle classification in the test. The reason for this is that the friction material of the present invention may be used for a large overseas motorcycle or a vehicle brake having a maximum speed exceeding 140 km / h.

  The friction characteristics were evaluated by the average friction coefficient in the second efficacy test, the minimum friction coefficient in the fade test in the first fade recovery test, and the wear amount of the friction material and the counterpart material after the test. The above evaluation results are summarized in Tables 6 and 7 below.

  The physical properties and friction characteristics of the friction material are shown in Tables 6 and 7. The required performance required for the friction material is shown in Table 8. In Tables 6 to 8, when the wear amount of the counterpart material is negative, it indicates that the thickness of the counterpart material has increased due to welding of the friction material. Regarding the room temperature shear strength of the unused friction material and the room temperature shear strength after the thermal shock test, the comparative products 1, 2 and 6 were below the required performance. Regarding the average friction coefficient of the second efficacy test and the minimum friction coefficient of the fade test of the first fade recovery test, both the invention product and the comparative product satisfy the required performance. Regarding the amount of wear of the friction material after the test, Comparative Products 1, 3, 5, and 9 have a large amount of wear of the friction material and do not satisfy the required performance. Regarding the wear amount of the mating material, Comparative products 1, 4 and 5 have a large wear amount of the mating material and do not satisfy the required performance. Since the comparative products 7-9 which are conventional products contain copper and nickel, they have a higher environmental load than the inventive products 1-9. On the other hand, although the invention product did not contain copper or nickel, it showed the same or better performance as the comparative products 7 to 9 containing copper and nickel.

  As described above, the friction material of the present invention has low environmental impact because it does not contain nickel, which is designated as a first-class designated chemical substance by the PRTR method, or copper, which has been discussed to be subject to regulation, Furthermore, it is not necessary to carry out the management required for the first-class designated chemical substances, and the cost is improved accordingly.

  Furthermore, as is clear from the examples, the friction material of the present invention has a friction coefficient equal to or higher than that of the conventional product, even though it does not contain nickel or copper, which has been used to increase the friction coefficient of the conventional friction material. In addition, some characteristics, such as the coefficient of friction at high temperatures, exceed those of conventional products.

  From the above, the friction material of the present invention is an excellent friction material in terms of environmental load, cost, friction characteristics, and the like, and various machines such as machine tools, construction machines, agricultural machines, automobiles, two-wheeled vehicles, railways, airplanes, and ships. It can be widely applied to means for arbitrarily controlling the rotation or movement of the.

Claims (8)

A friction material containing a friction modifier in a metal phase containing Fe and Si,
The friction modifier contains hard particles and a lubricating substance,
The lubricating substance contains graphite and calcium fluoride;
In the metal phase, the Fe element is contained in an amount of 70 to 98% by mass with respect to the entire metal phase, and the Si element is contained in an amount of 2 to 30% by mass with respect to the entire metal phase (however, the content of Fe element and the Si element The total content is 100% by mass or less, and the total amount of Al element and Mg element is 3% by mass or less based on the entire metal phase ), friction material. The content of the metal phase is 55 to 70% by mass with respect to the entire friction material,
The content of the friction modifier is 30 to 45% by mass with respect to the entire friction material,
The friction material according to claim 1, wherein the total content of the metal phase and the friction modifier is 100% by mass. The content of Fe element in the metal phase is 70 to 98% by mass,
The content of Si element in the metal phase is 2 to 30% by mass,
The friction material of Claim 1 or Claim 2 whose sum total of content of Fe element and Si element is 100 mass%.   The friction according to any one of claims 1 to 3, wherein the metal phase contains 15 mass% or less of a P element with respect to the entire metal phase instead of a part of the Fe element contained in the metal phase. Wood. The content of the hard particles is 10 to 20% by mass with respect to the entire friction material,
The content of the lubricating substance is 20 to 28% by mass with respect to the entire friction material,
The friction material according to any one of claims 1 to 4 , wherein a content of the friction modifier is 30 to 45 mass% with respect to the entire friction material. The content of the metal phase is 58 to 68 mass% with respect to the entire friction material,
The content of the friction modifier is 32-42% by mass with respect to the entire friction material,
The friction material according to any one of claims 1 to 5 , wherein a total content of the metal phase and the friction modifier is 100% by mass. The friction according to any one of claims 1 to 6 , wherein the metal phase contains 10 mass% or less of a P element with respect to the entire metal phase in place of a part of the Fe element contained in the metal phase. Wood. The hard particles are silica (SiO ₂ ), alumina (Al ₂ O ₃ ), magnesia (MgO), titania (TiO ₂ ), zirconia (ZrO ₂ ), yttria (Y ₂ O ₃ ), mullite (Al ₂ SiO _5). ), zircon sand (ZrSiO _4), tungsten steel (Fe? W) is at least one selected from the group consisting of tungsten carbide (WC) and silicon carbide (SiC), in any one of claims 1 to 7 The friction material described.