JP4109825B2 - Rust prevention method for sliding members using photocatalyst - Google Patents
Rust prevention method for sliding members using photocatalyst Download PDFInfo
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- JP4109825B2 JP4109825B2 JP2000326830A JP2000326830A JP4109825B2 JP 4109825 B2 JP4109825 B2 JP 4109825B2 JP 2000326830 A JP2000326830 A JP 2000326830A JP 2000326830 A JP2000326830 A JP 2000326830A JP 4109825 B2 JP4109825 B2 JP 4109825B2
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- photocatalyst
- rust
- sliding member
- metal sliding
- rust prevention
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- 239000011941 photocatalyst Substances 0.000 title claims description 40
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 title claims description 35
- 230000002265 prevention Effects 0.000 title claims description 16
- 238000000034 method Methods 0.000 title claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 239000002184 metal Substances 0.000 claims description 20
- 230000009471 action Effects 0.000 claims description 11
- 230000000694 effects Effects 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 14
- 239000010931 gold Substances 0.000 description 14
- 229910052737 gold Inorganic materials 0.000 description 14
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 238000003380 quartz crystal microbalance Methods 0.000 description 12
- 238000012360 testing method Methods 0.000 description 12
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 11
- 238000007747 plating Methods 0.000 description 11
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 8
- 239000011780 sodium chloride Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 229910000599 Cr alloy Inorganic materials 0.000 description 6
- 239000000788 chromium alloy Substances 0.000 description 6
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000005381 potential energy Methods 0.000 description 4
- 230000001603 reducing effect Effects 0.000 description 4
- 239000004408 titanium dioxide Substances 0.000 description 4
- 229910052724 xenon Inorganic materials 0.000 description 4
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 150000002927 oxygen compounds Chemical class 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- -1 that is Inorganic materials 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
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- Braking Arrangements (AREA)
- Catalysts (AREA)
- Prevention Of Electric Corrosion (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、オートバイ、自動車のブレーキディスク等の金属部材が摺動する箇所における錆の防止方法に関し、更に詳細には、当該摺動箇所で起こり易い錆を光触媒の酸化還元作用を活用して防止する方法に関する。
【０００２】
【従来の技術】
従来、オートバイ、自動車等のブレーキディスク部は錆の発生し易い箇所として注意の必要な部位であり、その理由は、以下の如くである。
（１）（酸化作用）
ブレーキディスク等では、ブレーキの作動と共にディスクの表面がブレーキ部材によって擦られている状態で、ディスク表面を形成する金属部材が摺動によって少しずつ摩耗される状態にある。
金属は酸化膜を形成して一旦安定化するが、上記摩耗によって酸化膜が削られると、新しい界面が露出される。
新しい界面は、空中の酸素との結合力が強く、容易に酸化金属即ち錆を発生させる原因となる。
（２）（熱作用）
同時に、摺動に伴う運動で摩擦熱が発生し、金属表面は４００℃程度にまで昇温し、すると、上記金属と空中酸素との反応性はアレニウスの式に従って幾何級数的に高まり、錆の発生の速度を著しく速める。
（３）（ポテンシャルエネルギー）
通常は、反応系は当初高いポテンシャルエネルギーを保持していても、経時と共に安定化の為に、ポテンシャルエネルギーを低める方向に系が進むが、摺動部にあって金属表面が削られると、一旦低下したポテンシャルエネルギーが再び高い位置に戻り、反応性の高い状態となる。
【０００３】
従って、各種ブレーキディスク等では、この錆を防止すべく表面に各種めっきを施す等の手段が講じられているが、摺動による摩耗が絶えず繰り返される状況にあってはめっきの作用にも限界があり、錆の発生は避けられない現状にある。
【０００４】
【発明が解決しようとする課題】
本発明は上記実状に鑑みてなされたもので、摺動と共に繰り返される酸化作用に対し、光の照射によって惹起される光触媒の還元作用を促す方途に着目し、鋭意研究を進めた結果、ここに錆発生の防止に著効あることを見いだし、本発明を完成させたものである。
【０００５】
【課題を解決するための手段】
請求項１に記載の防錆方法は、摩擦作用を受ける金属摺動部材に対し、光触媒を電気的に導通状態において、光触媒による還元作用で摺動部材の錆の発生を防止することを特徴として構成される。
請求項２に記載の防錆方法は、摺動部材の一部または全部に直接光触媒の層を形成して両者を直接導通状態として構成される。
請求項３に記載の防錆方法は、摺動部材と光触媒とを分離し、対象部材と連動する部材で光照射に好条件を備えた部位に光触媒を形成し、両者を導電性物質で導通状態に接続して構成される。
請求項４に記載の防錆方法は、摺動部材と光触媒とが分離され、且つ、作動する対象部材に対しブラシ等の電気的接続部材を介して光触媒を導通状態にして構成される。
【０００６】
【発明の実施の形態】
本発明の対象とする防錆部材は、金属部材であって、その部位に摺動によって摩擦が働く箇所をいい、典型例は、オートバイ、乗用車、貨物自動車、電車等のブレーキディスクを指すが、その他、軸と軸受等の機械部品の金属部材の摺動部をも広く含むものである。
【０００７】
一方、本発明で利用する光触媒とは、バンドキャップ以上のエネルギーを有する光が照射された場合、価電子帯から伝導帯へ電子が励起されて、伝導帯に電子が、価電子帯に正孔を生じる物質をいう。
例えば、二酸化チタン、酸化亜鉛等を挙げることができ、二酸化チタンには、結晶構造の違いによってルチル型とアナターゼ型とが存し、低温安定相であるアナターゼ型の方が活性である。酸化亜鉛は、熱的に比較的安定である。
【０００８】
そして、本発明にあっては、上記対象部材に対して、光触媒を電気的に導通状態に配設して構成される。
該導通状態には、下記の如き態様が挙げられる。
（ａ）例えば、ブレーキディスクにあっては、図１に示す如く、摺動部の存するディスク外周部に対して、ディスクの摺動部以外の部分（例えば中心部）に光触媒１を形成し、金属素材であるディスク（アルミニウム素地２、鉄クロム合金めっき部３）を介して対象部材と光触媒とを導通状態に置く態様とする。
即ち、対象部材の一部に直接光触媒の層を形成して両者を直接導通状態に配設する態様とする。
（ｂ）上記と同様のブレーキディスクにあって、対象部材と光触媒とを分離し、例えば摺動部の存するブレーキディスクに対し、これに同期して回転し、且つ、光照射の効率の良いホイールキャップの表面に光触媒を形成し、両者を導電性物質で導通状態に接続する。
即ち、対象部材と光触媒とを分離し、対象部材と連動する部材で、光照射に好条件を備えた部位に光触媒を形成し、両者を導電性物質で導通状態に接続する。
（ｃ）対象部材と光触媒とが分離され、且つ、作動する対象部材に対しブラシ等の電気的接続部材を介して光触媒を導通状態にする。
【０００９】
上記構成の本発明防錆方法の効果を確認する為、下記の如き、防錆試験を行った。
先ず、防錆の対象物として金基板を選び、その表面に鉄ークロムの合金めっきを施して水晶振動子マイクロバランス（ＱＣＭ）電極とした。基板を金としたのは、化学的に安定で、鉄ークロム合金めっきは防錆に用いられるめっきを代表させる為である。
一方、光触媒として二酸化チタンを選択し、板上に形成し、これにキセノンランプ等の光源を照射可能に配設した。
該対象物と光触媒のコーティングされた板体とを１％ＮａＣｌ水溶液に浸漬し、両者を導線で結合し、ＮａＣｌ水溶液による侵食で錆の発生する状態をＱＣＭ方式のプレーティングモニターにより、その重量変化を観察する装置を設定した（図２参照）。
【００１０】
即ち、鉄ークロムの合金めっきを施しＱＣＭ金電極４に交流電圧を印加すると、
（Ｓａｕｅｒｂｒｅｙの式）
ｍ／Ａ＝−Ｎｑ・ρ・（ｆｏ −ｆ）×１０６ ／ｆｏ ２
ｍ／Ａ：単位面積あたりの質量変化
Ｎｑ ：定数１．６６８×１０５（ｃｍ・Ｈｚ）
ρ：水晶の密度２．６４８（ｇ・ｃｍ−３）
ｆｏ：マイグレーション測定直前の水晶振動子電極の共振周波数（Ｈｚ）
ｆ：測定時の共振周波数（Ｈｚ）
により、質量の変化をナノグラム単位で測定でき、その質量変化から錆の発生状況を経時的に追跡したものである。
【００１１】
その結果を示すと図３の如くである。
光照射の無い（イ）は、開始と同時に重量減少が始まり、これは鉄クロムがＮａＣｌ溶液中に溶出していることを示し、その後、１５０００ｓｅｃ経過後付近から重量増加に転じて２００００ｓｅｃ付近まで増加が進むが、これは表面に酸化物が固定化し、不働態化が進んでいることを示している。さらに２２０００ｓｅｃ以降から再び重量減少が見られる。これは、溶液中に存在する塩化物イオンにより準安定の不働態の状態が破壊されて腐食反応が繰り返される為と推定される。
これに対し、光触媒にキセノンランプを照射した（ロ）では、若干の重量増加が見られるものの、増減のない極めて安定な状態を示し、錆の発生が可及的に抑制されてることが裏付けられた。
【００１２】
又、上記鉄ークロムの合金めっきを施したＱＣＭ金電極４の表面状態を映した写真を示すと図４〜図６の如くである。
防錆試験前の状態が図４の如くで、これを食塩水中に光照射の無い「暗状態下」で浸したものの写真が図５で、裏側の基板の金が露出し、腐食が強く進んでいることが判る。これに対し、光触媒にキセノンランプを照射した「光照射下」で浸した写真が図６で、裏側の金がまったく露出することなく、腐食が殆ど進んでいないことが確認された。
【００１３】
更に、上記ＱＣＭ金電極４の表面状態を走査電子顕微鏡写真（ＳＥＭ像）として撮影し、それを図７〜図９に示した。
防錆試験前のＳＥＭ像が図７の如くで、これを食塩水中に光照射の無い「暗状態下」で浸したもののＳＥＭ像が図８で、腐食試験前には細かく均一であった組織が変化し、腐食試験後には粗い粒子が多数存在することが判る。これに対し、光触媒にキセノンランプを照射した「光照射下」で浸したＳＥＭ像が図９で、「光照射下」では、ごく一部に若干の粒状物が観察されるが、それ以外は殆ど変化がなく、ここでも腐食が殆ど進んでいないことが確認された。
【００１４】
さらに、エネルギー分散型Ｘ線分析装置（ＥＤＸ）による表面元素分析を行い、それを下表１に示した。
【表１】
【００１５】
さて、上記各試験によって確認された本発明の防錆方法の作用は、以下の如く推察される。
例えば、ブレーキディスク等の表面を形成する金属部材が摺動によって少しずつ摩耗されると、酸素との結合力の強い新しい界面が表れると同時に、摺動に伴う高い摩擦熱が発生し、更にポテンショルエネルギーも高い位置に維持されるので、表面が化学的に活性な状態となり、容易に酸化され得る状態となる。
一方、半導体としての光触媒に光が照射されると、禁制帯に電荷分離が起こり、一方の伝導帯に電子が励起され、他方の価電子帯に正孔が生成され、強い酸化還元力を持つに至る。
従って、上記摩耗が部材の摺動に従って、絶えず、継続的に金属の酸化が進行するのに対し、一方の光触媒からは、光の照射に伴って、絶えず励起電子が誘起される状態となり、それが電気的導通状態に置かれると、電位差を埋めるべく酸化部位に対し継続的に電子供給が促されることとなる。
この結果、酸化が常態的に進行する摺動部材に、光エネルギーによる還元作用が継続的に働き、錆の発生を効率的に防止するものと推察される。
【００１６】
【実施例】
オートバイのブレーキディスクに軽量化を狙いとしてアルミニウムを素材として用い、その表面に防錆のために鉄ークロムめっきを施したものを採用した。
そのブレーキディスクの中心部に、光触媒として二酸化チタンを直接形成した。
これをオートバイに装着して、経時に表面の変化を目視によって観察し、その結果を下表２に示した。
【表２】
【００１７】
【発明の効果】
以上の構成及び作用によって本発明は以下の如き優れた効果を奏する。
（ａ）極めて錆の発生し易いブレーキディスク等の摺動部材に対し、光エネルギーによる還元作用を継続的に働かせ、錆の発生を極めて効率的に防止することができる。
（ｂ）その際、光という自然エネルギーを利用するので、特別な電力供給等を必要とせず、防錆効果を半永久的に持続させることができる。
（ｃ）光照射の可能な部位に光触媒の層を形成し、それと摺動部位とを電気的に導通状態に置けばよいので、装置として極めて軽量で且つ簡潔であり、動作の激しいディスクブレーキその他の装置に対しても、その機能を損じることが無い。
【図面の簡単な説明】
【図１】 ブレーキディスクの一部に光触媒を形成した態様の側面図。
【図２】 防錆の試験装置を示す斜視図。
【図３】防錆試験結果を示すグラフ。
【図４】防錆試験前のＱＣＭ金電極板の状態を示す写真。
【図５】 食塩水中に「暗状態下」で浸した後のＱＣＭ金電極板の状態を示す写真。
【図６】食塩水中に「光照射下」で浸した後のＱＣＭ金電極板の状態を示す写真。
【図７】防錆試験前のＱＣＭ金電極板の状態を示すＳＥＭ写真。
【図８】 食塩水中に「暗状態下」で浸した後の金基板上の鉄クロム合金めっきの板の状態を示すＳＥＭ写真。
【図９】食塩水中に「光照射下」で浸した後のＱＣＭ金電極板の状態を示すＳＥＭ写真。
【符号の説明】
１ 光触媒
２ アルミニウム素地
３ 鉄クロムめっき部
４ ＱＣＭ金電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preventing rust at a location where a metal member such as a motorcycle or an automobile brake disk slides, and more specifically, rust that tends to occur at the slide location is prevented by utilizing the redox action of a photocatalyst. On how to do.
[0002]
[Prior art]
Conventionally, brake disc parts of motorcycles, automobiles and the like are parts that require attention as places where rust is likely to occur, and the reason is as follows.
(1) (Oxidation effect)
In a brake disk or the like, a metal member forming the disk surface is gradually worn by sliding while the surface of the disk is rubbed by the brake member as the brake is operated.
The metal once stabilizes by forming an oxide film, but when the oxide film is shaved by the wear, a new interface is exposed.
The new interface has a strong bonding force with oxygen in the air and easily causes metal oxide, that is, rust.
(2) (Thermal action)
At the same time, frictional heat is generated by the movement accompanying sliding, and the metal surface is heated to about 400 ° C., and the reactivity of the metal with oxygen in the air increases geometrically according to the Arrhenius formula, Significantly increase the rate of occurrence.
(3) (Potential energy)
Normally, even if the reaction system initially retains a high potential energy, the system proceeds in the direction of decreasing the potential energy for stabilization over time, but once the metal surface is scraped in the sliding part, The lowered potential energy returns to a higher position, and the state becomes highly reactive.
[0003]
Therefore, various brake discs and the like are provided with various means such as plating on the surface to prevent this rust. However, there is a limit to the effect of plating in situations where wear due to sliding is constantly repeated. Yes, the occurrence of rust is inevitable.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and as a result of diligent research, focusing on a method for promoting the reduction action of the photocatalyst caused by light irradiation against the oxidation action repeated with sliding, The present invention has been completed by finding that it is effective for preventing rust.
[0005]
[Means for Solving the Problems]
The rust prevention method according to
The rust prevention method according to
According to a third aspect of the present invention, the sliding member and the photocatalyst are separated from each other, the photocatalyst is formed in a portion having favorable conditions for light irradiation by a member interlocking with the target member, and the two are made conductive by a conductive substance. Configured to connect to the state.
According to a fourth aspect of the present invention, the sliding member and the photocatalyst are separated from each other, and the photocatalyst is made conductive with respect to the target member to be operated via an electrical connection member such as a brush.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The rust preventive member to be the subject of the present invention is a metal member, which refers to a place where friction acts on the part by sliding, and a typical example refers to a brake disk of a motorcycle, a passenger car, a truck, a train, etc. In addition, the sliding part of the metal member of machine parts, such as a shaft and a bearing, is also included widely.
[0007]
On the other hand, the photocatalyst used in the present invention is that when light having energy higher than the band cap is irradiated, electrons are excited from the valence band to the conduction band, and electrons are transferred to the conduction band and holes to the valence band. A substance that produces
For example, titanium dioxide, zinc oxide and the like can be mentioned. Titanium dioxide has a rutile type and an anatase type depending on the crystal structure, and the anatase type which is a low-temperature stable phase is more active. Zinc oxide is thermally relatively stable.
[0008]
In the present invention, the photocatalyst is electrically connected to the target member.
Examples of the conductive state include the following modes.
(A) For example, in the brake disc, as shown in FIG. 1, the
That is, a mode in which a photocatalyst layer is directly formed on a part of the target member and both are placed in a direct conductive state.
(B) A brake disk similar to the above, wherein the target member and the photocatalyst are separated, and for example, a wheel that rotates in synchronization with a brake disk having a sliding portion and has high light irradiation efficiency. A photocatalyst is formed on the surface of the cap, and both are connected in a conductive state with a conductive substance.
That is, the target member and the photocatalyst are separated, and the photocatalyst is formed at a portion having favorable conditions for light irradiation by a member that works in conjunction with the target member, and both are connected to a conductive state by a conductive substance.
(C) The target member and the photocatalyst are separated, and the photocatalyst is brought into a conducting state with respect to the target member to be operated through an electrical connection member such as a brush.
[0009]
In order to confirm the effect of the rust prevention method of the present invention having the above-described configuration, a rust prevention test was conducted as follows.
First, a gold substrate was selected as an object to be rust-proofed, and an iron-chromium alloy plating was applied to the surface thereof to form a quartz crystal microbalance (QCM) electrode. The reason why the substrate is gold is that it is chemically stable and the iron-chromium alloy plating is representative of plating used for rust prevention.
On the other hand, titanium dioxide was selected as a photocatalyst, formed on a plate, and provided with a light source such as a xenon lamp.
The object and the plate coated with photocatalyst are immersed in a 1% NaCl aqueous solution, both are connected with a lead wire, and the weight change of the state in which rust is generated by erosion by the NaCl aqueous solution is measured by a QCM type plating monitor. Was set up (see FIG. 2).
[0010]
That is, when an AC voltage is applied to the QCM gold electrode 4 after applying an iron-chromium alloy plating,
(Sauerbrey's formula)
m / A = -N q · ρ · (f o -f) × 10 6 /
m / A: mass change per unit area N q : constant 1.668 × 10 5 (cm · Hz)
ρ: Crystal density 2.648 (g · cm −3 )
f o : Resonance frequency (Hz) of the crystal resonator electrode immediately before the migration measurement
f: Resonance frequency during measurement (Hz)
Thus, the change in mass can be measured in nanogram units, and the occurrence of rust is traced over time from the change in mass.
[0011]
The result is shown in FIG.
When there is no light irradiation (a), the weight starts to decrease at the same time as the start, which indicates that iron chromium is eluted in the NaCl solution, and then increases from about 15000 seconds to increase in weight to about 20000 seconds. However, this indicates that the oxide is fixed on the surface and the passivation is progressing. Furthermore, weight reduction is observed again after 22000 sec. This is presumed to be because the metastable passive state is destroyed by chloride ions present in the solution and the corrosion reaction is repeated.
In contrast, when the photocatalyst was irradiated with a xenon lamp (b), although there was a slight increase in weight, it showed an extremely stable state with no increase or decrease, confirming that the generation of rust was suppressed as much as possible. It was.
[0012]
FIGS. 4 to 6 show photographs showing the surface state of the QCM gold electrode 4 subjected to the iron-chromium alloy plating.
The state before the rust prevention test is as shown in FIG. 4, and a photograph of this immersed in a “dark state” without light irradiation in a saline solution is shown in FIG. 5. The gold on the back substrate is exposed, and the corrosion progresses strongly. You can see that On the other hand, a photograph immersed in “under light irradiation” in which the photocatalyst was irradiated with a xenon lamp was shown in FIG. 6, and it was confirmed that the gold on the back side was not exposed at all and the corrosion hardly progressed.
[0013]
Furthermore, the surface state of the QCM gold electrode 4 was photographed as a scanning electron micrograph (SEM image), which is shown in FIGS.
The SEM image before the rust prevention test is as shown in FIG. 7, and the SEM image of the sample immersed in a “dark state” without light irradiation in saline is shown in FIG. It can be seen that there are many coarse particles after the corrosion test. On the other hand, the SEM image immersed in “under light irradiation” in which the photocatalyst was irradiated with a xenon lamp is shown in FIG. 9. Almost no change was observed, and it was confirmed that the corrosion was hardly progressed here.
[0014]
Furthermore, surface elemental analysis was performed using an energy dispersive X-ray analyzer (EDX), which is shown in Table 1 below.
[Table 1]
[0015]
Now, the action of the rust-preventing method of the present invention confirmed by the above tests is presumed as follows.
For example, when a metal member that forms the surface of a brake disk or the like is gradually worn by sliding, a new interface having a strong binding force with oxygen appears, and at the same time, high frictional heat is generated due to sliding, which further increases the potential. Since the energy is also maintained at a high position, the surface becomes chemically active and can be easily oxidized.
On the other hand, when a photocatalyst as a semiconductor is irradiated with light, charge separation occurs in the forbidden band, electrons are excited in one conduction band, holes are generated in the other valence band, and have strong redox power To.
Therefore, the above-mentioned wear continuously oxidizes the metal as the member slides, whereas one photocatalyst is constantly in the state where excited electrons are induced by light irradiation. When placed in an electrically conductive state, the supply of electrons is continuously promoted to the oxidation site to fill the potential difference.
As a result, it is surmised that the reducing action by light energy continuously acts on the sliding member in which oxidation normally proceeds, and the generation of rust is effectively prevented.
[0016]
【Example】
For the purpose of reducing the weight of motorcycle brake discs, aluminum was used as the material, and the surface was iron-chrome plated for rust prevention.
Titanium dioxide was directly formed as a photocatalyst at the center of the brake disk.
This was mounted on a motorcycle and the change in the surface was observed with the lapse of time. The results are shown in Table 2 below.
[Table 2]
[0017]
【The invention's effect】
With the above configuration and operation, the present invention has the following excellent effects.
(A) A reducing action by light energy can be continuously applied to a sliding member such as a brake disk, which is very easy to generate rust, and the generation of rust can be prevented very efficiently.
(B) At that time, since natural energy of light is used, a special power supply or the like is not required, and the rust prevention effect can be maintained semipermanently.
(C) Since a photocatalyst layer is formed at a site where light irradiation is possible and the sliding portion is placed in an electrically conductive state, the device is extremely lightweight and simple, and the disc brake has a high performance. The function of this device is not impaired.
[Brief description of the drawings]
FIG. 1 is a side view of a mode in which a photocatalyst is formed on a part of a brake disc.
FIG. 2 is a perspective view showing a rust prevention test apparatus.
FIG. 3 is a graph showing the results of a rust prevention test.
FIG. 4 is a photograph showing a state of a QCM gold electrode plate before a rust prevention test.
FIG. 5 is a photograph showing a state of a QCM gold electrode plate after being immersed in a “dark state” in saline.
FIG. 6 is a photograph showing a state of a QCM gold electrode plate after being immersed in saline under “light irradiation”.
FIG. 7 is an SEM photograph showing a state of a QCM gold electrode plate before a rust prevention test.
FIG. 8 is an SEM photograph showing a state of an iron-chromium alloy plating plate on a gold substrate after being immersed in a “dark state” in saline.
FIG. 9 is an SEM photograph showing a state of a QCM gold electrode plate after being immersed in saline under “light irradiation”.
[Explanation of symbols]
1 Photocatalyst 2 Aluminum substrate 3 Iron chromium plating part 4 QCM gold electrode
Claims (3)
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| Application Number | Priority Date | Filing Date | Title |
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| JP2000326830A JP4109825B2 (en) | 2000-10-26 | 2000-10-26 | Rust prevention method for sliding members using photocatalyst |
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| JP2000326830A JP4109825B2 (en) | 2000-10-26 | 2000-10-26 | Rust prevention method for sliding members using photocatalyst |
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| JP4109825B2 true JP4109825B2 (en) | 2008-07-02 |
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| JP5705398B2 (en) * | 2007-12-05 | 2015-04-22 | トヨタ自動車株式会社 | Vehicle wheels and wheel caps |
| BR112018013275A2 (en) | 2015-12-31 | 2018-12-11 | Henkel Ag & Co Kgaa | self-priming coatings |
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