JPH04213042A - Method for evaluating and testing corrosiveness of exhaust-gas condensed water - Google Patents
Method for evaluating and testing corrosiveness of exhaust-gas condensed waterInfo
- Publication number
- JPH04213042A JPH04213042A JP40059390A JP40059390A JPH04213042A JP H04213042 A JPH04213042 A JP H04213042A JP 40059390 A JP40059390 A JP 40059390A JP 40059390 A JP40059390 A JP 40059390A JP H04213042 A JPH04213042 A JP H04213042A
- Authority
- JP
- Japan
- Prior art keywords
- ppm
- test
- condensed water
- corrosion
- exhaust gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000012360 testing method Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 44
- 238000005260 corrosion Methods 0.000 claims abstract description 64
- 230000007797 corrosion Effects 0.000 claims abstract description 64
- 238000010998 test method Methods 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 12
- 239000012085 test solution Substances 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 10
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 8
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 abstract description 7
- 230000008020 evaporation Effects 0.000 abstract description 7
- 239000007769 metal material Substances 0.000 abstract description 2
- 239000010935 stainless steel Substances 0.000 description 17
- 229910001220 stainless steel Inorganic materials 0.000 description 17
- 229910000831 Steel Inorganic materials 0.000 description 10
- 239000010959 steel Substances 0.000 description 10
- 150000002500 ions Chemical class 0.000 description 8
- 239000011521 glass Substances 0.000 description 5
- 238000007654 immersion Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000007747 plating Methods 0.000 description 3
- -1 CH3COO- Chemical compound 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、自動車排気系部材に使
用される金属材料の耐食性を評価する凝縮水腐食性評価
試験方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensed water corrosion evaluation test method for evaluating the corrosion resistance of metal materials used in automobile exhaust system members.
【０００２】0002
【従来の技術】従来から、自動車排ガス凝縮水に対する
自動車排気系材料の耐食性を評価する方法としては、Ｃ
ｌ− ， ＳＯ４２− ， ＣＯ３２− ， ＨＣＨＯ
， ＣＨ３ＣＯＯ− ， ＮＨ３ ＋ などを含む試験
溶液中に試験材料を半浸漬して試験する方法（たとえば
「自動車技術会前刷集」８７２昭和６２−１０ Ｐ．
６５１ 〜６５４ 、「日新製鋼技報」第５１号Ｐ．
１０２〜１１３ など参照）や試験片を同様の試験溶液
に浸漬した後、この溶液より取り出し乾燥させるいわゆ
るディップアンドドライ試験法（たとえば「鉄と鋼」１
９８５年Ｓ６７０ 参照）などが知られている。[Prior Art] Conventionally, as a method for evaluating the corrosion resistance of automobile exhaust system materials against automobile exhaust gas condensed water, C
l-, SO42-, CO32-, HCHO
, CH3COO- , NH3 + , etc. (for example, "Automotive Engineers of Japan Preprint Collection" 872, 1986-10 P.
651-654, "Nissin Steel Technical Report" No. 51, P.
102-113) or the so-called dip-and-dry test method in which a test piece is immersed in a similar test solution and then taken out and dried (for example, "Tetsu to Hagane" 1).
985 S670) are known.
【０００３】ここで、これらの試験法について簡単に説
明すると、前者の半浸漬試験法は図２に示すように、８
０℃一定の温水２を入れた恒温水槽１内に載置したガラ
スビーカ３に、試験片４が半分だけ浸漬するように試験
溶液５を入れ、ガラスビーカ３の上部を時計皿６で覆う
ようにして腐食状況を試験するものである。また、後者
のディップアンドドライ試験法は、図３に示すように、
試験溶液５が充満された薬品槽７内はヒータ８で５０℃
一定に調節され、その液中に試験片４が吊り装置９によ
って昇降可能とされ、３分間液中浸漬された後吊り上げ
られて熱風乾燥機１０からの８０℃の熱風で１７分間乾
燥される。
このサイクルを繰り返して腐食状況が試験される。[0003] Here, to briefly explain these test methods, the former half-immersion test method is as shown in FIG.
A test solution 5 is poured into a glass beaker 3 placed in a constant temperature water bath 1 containing hot water 2 kept at a constant 0°C so that the test piece 4 is only half immersed, and the top of the glass beaker 3 is covered with a watch glass 6. This is to test the corrosion status. In addition, the latter dip-and-dry test method, as shown in Figure 3,
The inside of the chemical tank 7 filled with the test solution 5 is kept at 50°C by the heater 8.
The test piece 4 is adjusted to a constant temperature and can be raised and lowered into the liquid by a hanging device 9, and after being immersed in the liquid for 3 minutes, it is lifted and dried with hot air at 80°C from a hot air dryer 10 for 17 minutes. This cycle is repeated to test for corrosion status.
【０００４】0004
【発明が解決しようとする課題】しかしながら、上記し
た半浸漬試験法やディップアンドドライ試験法ではたと
えばＡｌめっき鋼はよく腐食するものの、最近排気系材
料に採用されるようになったステンレス鋼、特に１６〜
２０ｗｔ％Ｃｒを含有する高耐食性ステンレス鋼では殆
ど腐食せず、耐食性を評価することができないと言う問
題を生じていた。[Problems to be Solved by the Invention] However, although the semi-immersion test method and dip-and-dry test method described above often corrode, for example, aluminum-plated steel, stainless steel, which has recently been adopted as exhaust system material, 16~
Highly corrosion-resistant stainless steel containing 20 wt% Cr hardly corrodes, resulting in the problem that corrosion resistance cannot be evaluated.
【０００５】本発明は、上記のような課題を解決すべく
なされたものであって、従来から排気系材料に用いられ
ていたＡｌめっき鋼のみならずステンレス鋼についても
、自動車排ガス凝縮水に対する耐食性を評価できる試験
方法を提供することを目的とする。The present invention has been made to solve the above-mentioned problems, and it is possible to improve the corrosion resistance of automobile exhaust gas condensed water not only for aluminum-plated steel, which has conventionally been used as an exhaust system material, but also for stainless steel. The purpose is to provide a test method that can evaluate the
【０００６】[0006]
【課題を解決するための手段】本発明は、自動車エンジ
ン排ガス凝縮水に対する自動車排気系材料の耐食性を評
価する試験を行う方法であって、上部にガスの排出口を
設け側部にガスの供給口を設けた密閉容器内に、重量割
合でＣｌ− ：１０〜５０００ｐｐｍ ， ＳＯ４２
−： １００〜１００００ ｐｐｍ ， ＳＯ３２−
： １００〜１００００ ｐｐｍ ，ＣＯ３２−： １
００〜１００００ ｐｐｍ ， ＮＨ４ ＋ ：１００
〜１００００ ｐｐｍ を含みｐＨ７〜１０に調整さ
れた試験溶液を所定の量だけ充填し、前記容器の上部に
試験片を吊り下げるとともに前記ガス供給口を介して前
記容器の上部にエンジン排ガス雰囲気を充満した後、前
記容器を５０〜１００ ℃に保持して前記溶液を蒸発さ
せ、この溶液が完全に蒸発したのち新たな試験溶液を補
充して前記排ガス雰囲気中での保持を繰り返し、全試験
時間が １００〜３０００時間になった時点で前記試験
片を取り出し、その錆方の程度で耐食性を評価すること
を特徴とする排ガス凝縮水腐食性評価試験方法である。[Means for Solving the Problems] The present invention is a method for conducting a test for evaluating the corrosion resistance of automobile exhaust system materials against automobile engine exhaust gas condensed water. In a sealed container with a mouth, Cl-: 10 to 5000 ppm by weight, SO42
−: 100 to 10000 ppm, SO32−
: 100-10000 ppm, CO32-: 1
00-10000 ppm, NH4 + :100
A predetermined amount of a test solution containing ~10,000 ppm and adjusted to pH 7 to 10 is filled, a test piece is suspended from the top of the container, and the top of the container is filled with engine exhaust gas atmosphere through the gas supply port. After that, the container is held at 50 to 100 °C to evaporate the solution, and after this solution has completely evaporated, a new test solution is added and the holding in the exhaust gas atmosphere is repeated, and the total test time is This is a test method for evaluating corrosion resistance of exhaust gas condensed water, characterized in that the test piece is taken out after 100 to 3000 hours, and the corrosion resistance is evaluated based on the degree of rust.
【０００７】なお、重量割合でＣｌ− ：１０〜５００
０ｐｐｍ ， ＳＯ４２−： １００〜１００００
ｐｐｍ ， ＳＯ３２− ：１００〜１００００ ｐｐ
ｍ ，ＣＯ３２−： １００〜１００００ ｐｐｍ ，
ＮＨ４ ＋ ：１００ 〜１００００ ｐｐｍ を含
み、さらにＨＣＨＯ：１〜１０００ｐｐｍ ， ＨＣＯ
Ｏ− ：１〜１０００ｐｐｍ ， ＣＨ３ＣＯＯ− ：
１〜１０００ｐｐｍ ， ＮＯ３ − ：１〜１００
ｐｐｍ のうちの１種または２種以上を含むｐＨ７〜１
０に調整された試験溶液を用いてもよい。[0007] In addition, Cl-: 10 to 500 in weight proportion
0ppm, SO42-: 100-10000
ppm, SO32-: 100-10000 ppm
m, CO32-: 100-10000 ppm,
Contains NH4+: 100 to 10,000 ppm, and further contains HCHO: 1 to 1,000 ppm, HCO
O-: 1-1000ppm, CH3COO-:
1~1000ppm, NO3-: 1~100
pH 7 to 1 containing one or more of ppm
A test solution adjusted to 0 may also be used.
【０００８】[0008]
【作 用】本発明者らは、前記した課題を解決するた
めに、自動車マフラーの腐食機構を詳細に調査した結果
、排気系材料の腐食は凝縮水が溜まるマフラー下部のみ
ならず、上部の気相部分でも結露した凝縮水により激し
く腐食することを知見した。また、ラボ実験においても
試験片の凝縮水中に浸漬した部分よりも、結露する気相
部分においてより腐食することを発見した。さらに、ス
テンレス鋼の腐食は ＳＯ３２−がかなり濃縮した時に
促進されるが、このような ＳＯ３２−の濃縮は排気ガ
ス中での溶液の蒸発濃縮を行った際に生じることを発見
した。なお、通常の大気中での溶液の蒸発では ＳＯ３
２−が酸化されて ＳＯ４２−に変化するため、 ＳＯ
３２−の濃縮は生じない。[Function] In order to solve the above-mentioned problems, the present inventors conducted a detailed investigation into the corrosion mechanism of automobile mufflers, and found that corrosion of exhaust system materials occurs not only in the lower part of the muffler where condensed water accumulates, but also in the upper part of the muffler. It was discovered that even the phase part was severely corroded by condensed water. In addition, in laboratory experiments, it was discovered that the gas phase portion of the test piece where condensation was formed was more corroded than the portion immersed in the condensed water. Furthermore, it has been discovered that corrosion of stainless steel is accelerated when SO32- is significantly concentrated, and that such concentration of SO32- occurs when the solution is evaporated and concentrated in exhaust gas. In addition, in the evaporation of a solution in normal air, SO3
2- is oxidized and changes to SO42-, so SO
No enrichment of 32- occurs.
【０００９】ここで本発明の構成要素を説明すると、自
動車排ガス凝縮水にはＣｌ− ， ＳＯ４２− ， Ｓ
Ｏ３２− ， ＣＯ３２− ， ＮＨ４ ＋ が数ｐｐ
ｍ から数 １００ｐｐｍ の範囲で含まれていること
が報告されており、これらは凝縮水腐食には不可欠のイ
オンと考えられる。また、ＨＣＨＯ， ＨＣＯＯ− ，
ＣＨ３ＣＯＯ− ， ＮＯ３ − も検出される場合
があり、その場合をシミュレートする試験においてはこ
れらのイオンを添加する必要がある。そこで、これらの
イオンの濃度を凝縮水腐食の再現性と加速性から以下の
ように定めた。
・Ｃｌ− ：Ｃｌ− は１０ｐｐｍ 未満ではステンレ
ス鋼の孔食が発生し難く、５０００ｐｐｍ を超えると
ステンレス鋼の腐食がＡｌめっき鋼に比べて促進され過
ぎるため、適性範囲を１０〜５０００ｐｐｍ とした。
・ＳＯ４２− ：ＳＯ４２− は凝縮水腐食を生じさせ
る主要因と考えられ、 １００ｐｐｍ 未満では凝縮水
腐食が生じ難く、１００００ ｐｐｍ を超えるとＡｌ
めっき鋼の腐食がステンレス鋼に比べて促進され過ぎる
ため、適性範囲を １００〜１００００ ｐｐｍ とし
た。
・ＳＯ３２− ：ＳＯ３２− はステンレス鋼の不動態
皮膜を還元破壊する作用があり、高Ｃｒ系のステンレス
鋼に凝縮水腐食を生じさせるためには １００ｐｐｍ
以上が必要である。しかし、 １００００ｐｐｍ を超
えるとステンレス鋼の腐食がＡｌめっき鋼に比べて促進
され過ぎるため、適性範囲を １００〜１００００ ｐ
ｐｍ とした。
・ＣＯ３２− ：ＣＯ３２− は蒸発濃縮する過程でＣ
Ｏ２ ガスとして蒸発し、濃縮時の溶液のｐＨをコント
ロールする。 １００ｐｐｍ 未満では濃縮時の溶液の
ｐＨが低くなり過ぎるために低Ｃｒ系のステンレスに孔
食が発生せず、全面溶解となり実際の凝縮水腐食を再現
しなくなる。また、 １００００ｐｐｍ を超えると濃
縮時の溶液のｐＨが高くなり過ぎるためステンレス鋼に
孔食が発生し難くなるため、適性範囲を １００〜１０
０００ ｐｐｍ とした。なお、ＣＯ３２− は水溶液
中ではｐＨに応じてＨＣＯ３− に変化するから、した
がって添加物ではＣＯ３２− であっても水溶液中では
ＣＯ３２− とＨＣＯ３− の両方のイオンとして存在
することになる。
・ＮＨ４ ＋ ：ＮＨ４ ＋ は排ガス浄化対策として
３元触媒を採用するようになってから凝縮水中に増加し
たイオンであり、このイオンにより凝縮水がアルカリ性
となっている。[0009] Here, to explain the constituent elements of the present invention, automobile exhaust gas condensed water contains Cl-, SO42-, S
Several pp of O32-, CO32-, NH4 +
It has been reported that the content ranges from 200 ppm to several 100 ppm, and these ions are considered essential for condensed water corrosion. Also, HCHO, HCOO-,
CH3COO- and NO3- may also be detected, and it is necessary to add these ions in a test simulating this case. Therefore, the concentrations of these ions were determined as follows from the viewpoint of reproducibility and acceleration of condensed water corrosion. -Cl-: If Cl- is less than 10 ppm, pitting corrosion of stainless steel is difficult to occur, and if it exceeds 5000 ppm, corrosion of stainless steel is accelerated more than Al-plated steel, so the appropriate range was set at 10 to 5000 ppm.・SO42-: SO42- is considered to be the main factor causing condensed water corrosion, and if it is less than 100 ppm, condensed water corrosion is difficult to occur, and if it exceeds 10,000 ppm, it will cause Al
Since corrosion of plated steel is accelerated more than that of stainless steel, the appropriate range is set to 100 to 10,000 ppm.・SO32-: SO32- has the effect of reducing and destroying the passive film of stainless steel, and in order to cause condensed water corrosion on high Cr stainless steel, 100 ppm is required.
The above is necessary. However, if it exceeds 10,000 ppm, the corrosion of stainless steel will be accelerated compared to Al-plated steel, so the appropriate range should be set at 100 to 10,000 ppm.
pm.・CO32-: CO32- is converted into C in the process of evaporation and concentration.
It evaporates as O2 gas and controls the pH of the solution during concentration. If it is less than 100 ppm, the pH of the solution during concentration will be too low, so pitting corrosion will not occur in low Cr stainless steel, and it will be completely dissolved, making it impossible to reproduce actual condensed water corrosion. In addition, if it exceeds 10,000 ppm, the pH of the solution during concentration becomes too high, making it difficult for pitting corrosion to occur in stainless steel, so the appropriate range is set to 100 to 10.
000 ppm. Note that in an aqueous solution, CO32- changes to HCO3- depending on the pH, so even if the additive is CO32-, it will exist as both CO32- and HCO3- ions in the aqueous solution.・NH4 + :NH4 + is an ion that has increased in condensed water since the adoption of three-way catalysts as a measure for exhaust gas purification, and this ion makes the condensed water alkaline.
【００１０】１００ｐｐｍ 未満では凝縮水がアルカリ
性とならずＡｌめっき層のアルカリ腐食が生じず、また
１００００ｐｐｍ を超えると濃縮時のｐＨが酸性に
ならず、ステンレス鋼の孔食が発生し難くなるため、適
性範囲を １００〜１００００ ｐｐｍ とした。以上
が凝縮水腐食を再現するための基本イオンであるが、さ
らに腐食を促進させるために以下のイオンの１種以上を
添加する必要がある。
・ＨＣＯＯ −，ＣＨ３ＣＯＯ −：ＨＣＯＯ− ，Ｃ
Ｈ３ＣＯＯ− はカルボン酸イオンであり、Ａｌめっき
鋼の腐食を促進させる。１ｐｐｍ 未満では腐食の促進
が不十分であり、 １０００ ｐｐｍ を超えると腐食
の再現性が損なわれるので適性範囲を１〜１０００ｐｐ
ｍ とした。・ＨＣＨＯ：ホルムアルデヒドは酸化され
てギ酸となり、Ａｌめっき鋼の腐食を促進させる。１ｐ
ｐｍ 未満では腐食の促進が不十分であり、１０００ｐ
ｐｍ を超えると腐食の再現性が損なわれるので適性範
囲を１〜１０００ｐｐｍ とした。
・ＮＯ３ − ：ＮＯ３ − は酸化剤として働き腐食
を促進させる。１ｐｐｍ 未満では腐食の促進が不十分
であり、 １００ｐｐｍ を超えると逆にステンレス鋼
を不動態化させるため、適性範囲を１〜１００ ｐｐｍ
とした。
・ｐＨ：凝縮水のｐＨは弱アルカリであることが報告さ
れており、ｐＨ７未満ではＡｌめっき層のアルカリ腐食
が生じず、ｐＨ１０を超えるとＡｌめっき層が腐食し過
ぎること、ステンレス鋼が腐食し難くなるため適性範囲
をｐＨ７〜１０とした。
・排気ガス：実車マフラー内に結露滞留する凝縮水およ
びマフラー内壁は、排気ガス流中にさらされている。排
気ガスの組成はＮ２， ＳＯ２， ＣＯ， ＣＯ２，
ＮＨ３， ＮＯ， ＮＯ２，ＮＯＸ さらには微量のＯ
２などと考えられ、実車マフラー内での凝縮水の蒸発濃
縮過程においてはこれらの成分が凝縮水中に溶解し、凝
縮水中イオン濃度の挙動を変化させる。
つまりＳＯ２ により、凝縮水中ＳＯ３２− は蒸発濃
縮過程において濃化し、ＮＨ３， ＣＯ２，ＣＯは凝縮
水中ＮＨ４ ＋ ， ＣＯ３２− の挙動を変化させ、
ｐＨの挙動に影響する。[0010] If it is less than 100 ppm, the condensed water will not become alkaline and alkaline corrosion of the Al plating layer will not occur, and if it exceeds 10,000 ppm, the pH during concentration will not become acidic and pitting corrosion of stainless steel will not occur easily. The appropriate range was set to 100 to 10,000 ppm. The above are the basic ions for reproducing condensed water corrosion, but in order to further promote corrosion, it is necessary to add one or more of the following ions.・HCOO-, CH3COO-:HCOO-,C
H3COO- is a carboxylic acid ion and accelerates corrosion of Al-plated steel. If it is less than 1 ppm, corrosion promotion is insufficient, and if it exceeds 1000 ppm, the reproducibility of corrosion will be impaired, so the appropriate range is 1 to 1000 ppm.
m.・HCHO: Formaldehyde is oxidized to form formic acid, which accelerates corrosion of Al-plated steel. 1p
Below 1000p, corrosion promotion is insufficient.
If it exceeds pm, the reproducibility of corrosion will be impaired, so the appropriate range is set to 1 to 1000 ppm.・NO3 − :NO3 − acts as an oxidizing agent and promotes corrosion. If it is less than 1 ppm, corrosion promotion is insufficient, and if it exceeds 100 ppm, it will passivate the stainless steel, so the appropriate range is 1 to 100 ppm.
And so.・pH: It has been reported that the pH of condensed water is weakly alkaline, and if the pH is less than 7, alkaline corrosion of the Al plating layer will not occur, and if the pH exceeds 10, the Al plating layer will be too corroded and stainless steel will corrode. Therefore, the appropriate range was set to pH 7 to 10.・Exhaust gas: Condensed water that accumulates inside the muffler of an actual vehicle and the muffler inner wall are exposed to the exhaust gas flow. The composition of exhaust gas is N2, SO2, CO, CO2,
NH3, NO, NO2, NOX and even trace amounts of O
During the evaporation and concentration process of condensed water in the muffler of an actual vehicle, these components dissolve in the condensed water and change the behavior of the ion concentration in the condensed water. In other words, due to SO2, SO32- in condensed water is concentrated in the evaporation concentration process, and NH3, CO2, and CO change the behavior of NH4 + and CO32- in condensed water.
Affects pH behavior.
【００１１】大気中および実車排ガス中での凝縮水濃縮
実験を行いｐＨの変化を測定したところ、初期ｐＨが約
９の凝縮水は濃縮するに従いｐＨの低下を生じるが、そ
の値には大気中と排ガス中とでは差を生じ、大気中が約
４、排ガス中では約７であった。このような中性域にお
いてはＡｌの孔食発生が促進されるため、実車腐食で観
察されるようなＡｌのピット状腐食が再現されると考え
られる。また、ステンレス鋼は低ｐＨ域で腐食が促進さ
れるため、腐食試験環境中ｐＨは腐食状況を大きく変化
させる。[0011] Condensed water concentration experiments were carried out in the atmosphere and in the exhaust gas of actual vehicles, and changes in pH were measured. It was found that condensed water with an initial pH of about 9 decreases in pH as it condenses; There was a difference between the amount and the amount in the exhaust gas, with the amount in the atmosphere being about 4 and the amount in the exhaust gas being about 7. Since pitting corrosion of Al is promoted in such a neutral region, it is thought that the pit-like corrosion of Al observed in actual vehicle corrosion is reproduced. Furthermore, since corrosion of stainless steel is accelerated in a low pH range, the pH in the corrosion test environment greatly changes the corrosion state.
【００１２】本発明における試験方法では実車排ガスを
用いており、任意のエンジン側条件の設定およびその組
み合わせが容易であり、より実車に近似した腐食環境を
再現することが可能である。なお、排ガスの温度条件や
試験時間，試験方法については以下による。
・温度：
排ガスの露点は５０℃付近にあり、これ以上の温度で凝
縮水が蒸発、濃縮する時に腐食が激しくなる。５０℃未
満では腐食が促進されず、 １００℃以上では蒸発が速
くなり過ぎ腐食させる時間が無くなるため、適性範囲を
５０〜１００ ℃とした。
・試験時間：
試験時間は １００時間未満では特にＡｌめっき鋼の腐
食が不十分であり、３０００時間を超えると結果が出る
までに時間がかかり過ぎること、および材料間の耐食性
の相対評価としては一定となり無駄な時間となることな
どの理由から、適性範囲を１００〜３０００時間とした
。
・試験方法：
試験片を溶液の直上に設置し、試験片表面に蒸発した凝
縮水を結露させることが本試験方法のポイントである。
このような結露した溶液が蒸発濃縮する過程で腐食が著
しく促進される。試験片の設置は水面に対して垂直でも
水平でも、斜め置きでもよい。液面からの距離は、試験
容器にもよるが５０ｃｍ以下であることが望ましい。
＜実施例＞
以下の実施例に基づいて本発明を説明する。まず、試験
装置としては、図１に示すように、恒温水槽１に水２を
張り、その中に試験溶液５を ３００ｍｌ入れたガラス
製の密閉容器１１を載置し、その上部に取付けたガラス
フック１２にナイロン糸１３を介して試験片４を吊った
。また、密閉容器１１の側部にはガス供給管１４がその
供給口１４ａが液面の上部に臨むように設けられ、その
上部にはガス排出管１５が取付けられている。そして、
ガス供給管１４からは流量計１６を介して実車排ガス１
７が密閉容器１１内に送り込まれる。The test method of the present invention uses exhaust gas from an actual vehicle, and it is easy to set and combine arbitrary engine conditions, making it possible to reproduce a corrosive environment more similar to that of an actual vehicle. The exhaust gas temperature conditions, test time, and test method are as follows.・Temperature: The dew point of exhaust gas is around 50°C, and corrosion becomes severe when condensed water evaporates and concentrates at temperatures above this temperature. If the temperature is lower than 50°C, corrosion will not be promoted, and if it is higher than 100°C, evaporation will be too rapid and there will be no time for corrosion, so the appropriate range is set at 50 to 100°C.・Test time: If the test time is less than 100 hours, the corrosion of Al-plated steel will be insufficient, and if it exceeds 3,000 hours, it will take too long to get a result, and the relative evaluation of corrosion resistance between materials will not be constant. Because of the reason that this would be a waste of time, the appropriate range was set to 100 to 3000 hours.・Test method: The key point of this test method is to place the test piece directly above the solution and allow the evaporated condensed water to condense on the test piece surface. Corrosion is significantly accelerated in the process of evaporation and concentration of such a dew-condensed solution. The test piece may be placed vertically, horizontally, or diagonally to the water surface. The distance from the liquid surface is preferably 50 cm or less, although it depends on the test container. <Examples> The present invention will be explained based on the following examples. First, as shown in Fig. 1, the test apparatus is a thermostatic water tank 1 filled with water 2, a glass airtight container 11 containing 300 ml of the test solution 5 placed therein, and a glass container attached to the top of the container 11. The test piece 4 was hung from the hook 12 via a nylon thread 13. Further, a gas supply pipe 14 is provided on the side of the closed container 11 so that its supply port 14a faces the upper part of the liquid level, and a gas discharge pipe 15 is attached to the upper part of the gas supply pipe 14. and,
Exhaust gas 1 from the actual vehicle is supplied from the gas supply pipe 14 via a flow meter 16.
7 is sent into the closed container 11.
【００１３】そこで、供試材として８０ｇ／ｍ２ 目付
のＡｌめっき鋼と、１１％Ｃｒ−０．２ ％ＴｉのＳＵ
Ｈ４０９Ｌ と、１７％ＣｒのＳＵＳ４３０と、１９％
Ｃｒ− ０．５％Ｎｂ− ０．５％ＣｕのＳＵＳ４３０
ＬＸの４種類の１ｍｍ厚の冷延焼鈍板を用いて、それぞ
れから試験片４として１ｍｍｔ×５０ｍｍＷ× １００
ｍｍＬの板を切り出して密閉容器１１内に吊り下げ、表
１，表２に示す試験条件でTherefore, the test materials were Al-plated steel with a basis weight of 80 g/m2 and SU with 11% Cr-0.2% Ti.
H409L, 17% Cr SUS430, 19%
Cr- 0.5%Nb- 0.5%Cu SUS430
Using four types of 1mm thick cold rolled annealed plates of LX, test pieces 4 of 1mmt x 50mmW x 100
A plate of mmL was cut out and suspended in a sealed container 11, and tested under the test conditions shown in Tables 1 and 2.
【００１４】[0014]
【表１】[Table 1]
【００１５】[0015]
【表２】[Table 2]
【００１６】試験片表面に凝縮水を結露， 蒸発， 濃
縮させた。なお、試験溶液５が２４時間で蒸発して無く
なるようにガス流量をコントロールした。また、比較の
ために半浸漬試験法（前出図２）と、ディップアンドド
ライ試験法（前出図３）とを併せて行い比較例とした。
それらの試験結果を表３に示した。なお、耐食性の評価
は、材料寿命として最も問題となる最大浸食深さにより
行った。[0016] Condensed water was condensed, evaporated, and concentrated on the surface of the test piece. Note that the gas flow rate was controlled so that the test solution 5 evaporated and disappeared within 24 hours. For comparison, a semi-immersion test method (see Figure 2 above) and a dip-and-dry test method (see Figure 3 above) were also conducted as a comparative example. The test results are shown in Table 3. The corrosion resistance was evaluated based on the maximum corrosion depth, which is the most important problem in terms of material life.
【００１７】[0017]
【表３】[Table 3]
【００１８】表３の結果からわかるように、比較例では
ステンレス鋼の腐食が微小あるいはＡｌめっき鋼に比べ
て過大となり、実車マフラーにおける凝縮水腐食を正確
に評価し得ていない結果となっているのに比べ、本発明
例に従えば各鋼種間の耐食性の差が明らかであり、かつ
適切な結果が得られることがわかる。特に、試験におい
て用いる排ガス組成を実車マフラー内の環境変化と同じ
形で連続的かつ簡便に変化させることが可能であり、上
記の効果と併せて適切な排気系材料の選定ができる。[0018] As can be seen from the results in Table 3, in the comparative example, the corrosion of stainless steel was minute or excessive compared to aluminum-plated steel, making it impossible to accurately evaluate condensed water corrosion in the muffler of an actual vehicle. In comparison, it can be seen that according to the examples of the present invention, the difference in corrosion resistance between the steel types is clear and appropriate results can be obtained. In particular, it is possible to continuously and easily change the exhaust gas composition used in the test in the same manner as the environmental change in the muffler of an actual vehicle, and in addition to the above effects, it is possible to select an appropriate exhaust system material.
【００１９】[0019]
【発明の効果】以上説明したように本発明によれば、鋼
種間の凝縮水腐食に対する耐食性の差を評価することが
可能となり、その結果適切な排気系材料の選定ができる
ようになるから、その寄与するところが大である。[Effects of the Invention] As explained above, according to the present invention, it becomes possible to evaluate the difference in corrosion resistance against condensed water corrosion between steel types, and as a result, it becomes possible to select an appropriate exhaust system material. Its contribution is significant.
【図１】本発明に用いる試験装置の説明図である。FIG. 1 is an explanatory diagram of a test device used in the present invention.
【図２】従来の半浸漬試験法に用いられる試験装置の説
明図である。FIG. 2 is an explanatory diagram of a test device used in a conventional semi-immersion test method.
【図３】従来のディップアンドドライ試験法に用いられ
る試験装置の説明図である。FIG. 3 is an explanatory diagram of a test device used in a conventional dip-and-dry test method.
１ 恒温水槽 ２ 水 ４ 試験片 ５ 試験溶液 １１ 密閉容器 １４ ガス供給管 １５ ガス排出管 １７ 実車排ガス 1 Constant temperature water tank 2. Water 4 Test piece 5 Test solution 11 Airtight container 14 Gas supply pipe 15 Gas exhaust pipe 17 Actual vehicle exhaust gas
Claims (2)
自動車排気系材料の耐食性を評価する試験を行う方法で
あって、上部にガスの排出口を設け側部にガスの供給口
を設けた密閉容器内に、重量割合でＣｌ− ：１０〜５
０００ｐｐｍ ， ＳＯ４２−： １００〜１０００
０ ｐｐｍ ， ＳＯ３２− ： １００〜１００００
ｐｐｍ ，ＣＯ３２−： １００〜１００００ ｐｐ
ｍ， ＮＨ４ ＋ ：１００ 〜１００００ ｐｐｍ
を含みｐＨ７〜１０に調整された試験溶液を所定の量だ
け充填し、前記容器の上部に試験片を吊り下げるととも
に前記ガス供給口を介して前記容器の上部にエンジン排
ガス雰囲気を充満した後、前記容器を５０〜１００ ℃
に保持して前記溶液を蒸発させ、この溶液が完全に蒸発
したのち新たな試験溶液を補充して前記排ガス雰囲気中
での保持を繰り返し、全試験時間が １００〜３０００
時間になった時点で前記試験片を取り出し、その錆方の
程度で耐食性を評価することを特徴とする排ガス凝縮水
腐食性評価試験方法。[Claim 1] A method for conducting a test to evaluate the corrosion resistance of automobile exhaust system materials against automobile engine exhaust gas condensed water, the method comprising: testing the corrosion resistance of automobile exhaust system materials against automobile engine exhaust gas condensed water; , Cl- in weight proportion: 10-5
000ppm, SO42-: 100-1000
0 ppm, SO32-: 100-10000
ppm, CO32-: 100-10000 ppm
m, NH4+: 100 to 10000 ppm
After filling a predetermined amount of a test solution with a pH of 7 to 10, suspending the test piece from the top of the container, and filling the top of the container with an engine exhaust gas atmosphere through the gas supply port, The container is heated to 50-100℃
After this solution has completely evaporated, a new test solution is replenished and the holding in the exhaust gas atmosphere is repeated for a total test time of 100 to 3,000 hours.
A test method for evaluating corrosion resistance of exhaust gas condensed water, characterized in that the test piece is taken out at a certain time, and corrosion resistance is evaluated based on the degree of rust.
ｐｐｍ ， ＳＯ４２−： １００〜１００００ ｐ
ｐｍ， ＳＯ３２− ： １００〜１００００ ｐｐｍ
，ＣＯ３２−： １００〜１００００ ｐｐｍ ，
ＮＨ４ ＋ ：１００ 〜１００００ ｐｐｍ を含み
、さらにＨＣＨＯ：１〜１０００ｐｐｍ ， ＨＣＯＯ
−：１〜１０００ｐｐｍ ， ＣＨ３ＣＯＯ− ：１〜
１０００ｐｐｍ ， ＮＯ３ − ：１〜１００ ｐｐ
ｍ のうちの１種または２種以上を含むｐＨ７〜１０に
調整された試験溶液を用いることを特徴とする請求項１
記載の試験方法。[Claim 2] Cl-: 10 to 5000 in weight proportion
ppm, SO42-: 100-10000 p
pm, SO32-: 100-10000 ppm
, CO32-: 100-10000 ppm,
Contains NH4+: 100 to 10,000 ppm, and further contains HCHO: 1 to 1,000 ppm, HCOO
-: 1~1000ppm, CH3COO-: 1~
1000ppm, NO3 −: 1 to 100ppm
Claim 1, characterized in that a test solution containing one or more of m and whose pH is adjusted to 7 to 10 is used.
Test method described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP40059390A JPH04213042A (en) | 1990-12-06 | 1990-12-06 | Method for evaluating and testing corrosiveness of exhaust-gas condensed water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP40059390A JPH04213042A (en) | 1990-12-06 | 1990-12-06 | Method for evaluating and testing corrosiveness of exhaust-gas condensed water |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04213042A true JPH04213042A (en) | 1992-08-04 |
Family
ID=18510489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP40059390A Pending JPH04213042A (en) | 1990-12-06 | 1990-12-06 | Method for evaluating and testing corrosiveness of exhaust-gas condensed water |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04213042A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102279150A (en) * | 2011-06-23 | 2011-12-14 | 长安大学 | Road material corrosion testing machine |
| CN102519864A (en) * | 2011-12-28 | 2012-06-27 | 昆明理工大学 | Building material liquid washing simulation test method and device thereof |
| CN107843482A (en) * | 2017-11-27 | 2018-03-27 | 中国石油天然气集团公司 | A kind of middle large scale test specimen cryogenic box |
| JP2020060420A (en) * | 2018-10-09 | 2020-04-16 | 株式会社Ihi | Deposit test device |
-
1990
- 1990-12-06 JP JP40059390A patent/JPH04213042A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102279150A (en) * | 2011-06-23 | 2011-12-14 | 长安大学 | Road material corrosion testing machine |
| CN102519864A (en) * | 2011-12-28 | 2012-06-27 | 昆明理工大学 | Building material liquid washing simulation test method and device thereof |
| CN107843482A (en) * | 2017-11-27 | 2018-03-27 | 中国石油天然气集团公司 | A kind of middle large scale test specimen cryogenic box |
| CN107843482B (en) * | 2017-11-27 | 2024-04-02 | 中国石油天然气集团公司 | Low-temperature box for medium-and-large-size test piece |
| JP2020060420A (en) * | 2018-10-09 | 2020-04-16 | 株式会社Ihi | Deposit test device |
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