CN102564932A - Method for determining magnesium or magnesium alloy corrosion rate and special experimental device - Google Patents
Method for determining magnesium or magnesium alloy corrosion rate and special experimental device Download PDFInfo
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- CN102564932A CN102564932A CN2011104477374A CN201110447737A CN102564932A CN 102564932 A CN102564932 A CN 102564932A CN 2011104477374 A CN2011104477374 A CN 2011104477374A CN 201110447737 A CN201110447737 A CN 201110447737A CN 102564932 A CN102564932 A CN 102564932A
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- magnesium
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- magnesium alloy
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- corrosion rate
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Abstract
The invention discloses a method for determining a magnesium or magnesium alloy corrosion rate and a special experimental device, which have the characteristics of high sensitivity and capabilities of obtaining an average corrosion rate, monitoring an instantaneous corrosion rate simultaneously, converting a hydrogen gas release rate into the instantaneous corrosion rate through collecting and determining the hydrogen gas release rate in a magnesium alloy corrosion process, and obtaining more information about the corrosion process. A hopper is inversely covered on a container with a corrosive medium; a magnesium metal or magnesium alloy specimen is hung inside the hopper; a burette is further inversely covered on the tail end of the hopper; the burette mouth is lower than the liquid level of the corrosive medium; a vacuumization operation is carried out inside the burette, and the solution in the burette is sucked to the highest scale of the burette; the burette is sealed; hydrogen gas, generated through the corrosion of the magnesium metal or magnesium alloy specimen, enters into the space above the liquid level of the burette in a bubble form through the hopper; an amount of the hydrogen gas generated on a unit surface area in unit corrosion time is read through the descending scale change of the liquid level; and the instantaneous corrosion rate or the average corrosion rate of magnesium metal or magnesium alloy on a certain moment is calculated.
Description
Technical field
The present invention relates to a kind of method and special-purpose experimental provision of measuring magnesium or magnesium alloy corrosion rate; Can be applicable to research easily through collecting and measuring the amount of release hydrogen in the corrosion process and the corrosion rate that speed is calculated magnesium and magnesium alloy to magnesium and magnesium alloy corrosion behavior.
Background technology
Magnesium is one of the lightest metal, and its density has only 1.7g/cm
3Magnesium alloy has high specific stiffness and specific strength, therefore under current energy-saving and cost-reducing international background, by increasing automobile transportation, electronics, the aerospace industry of being applied to.In addition, magnesium reserves on earth are very abundant, and the content in the earth's crust can account for 2.7% approximately, and content about 0.13% in the seawater.China is one of the abundantest country of magnesium resource in the world, so the development of China's magnesium industry has great potential and prospect.Yet; The chemical activity of magnesium has determined that the corrosion stability of magnesium is very poor; In various applied environments, might influence Application of Magnesium effect or life-span because of etching problem; Also can therefore improve the Application of Magnesium cost greatly, we can say that etching problem is that restriction magnesium is in one of each field key in application problem.Therefore the anti-corrosion problem of studying magnesium alloy is current material science worker's a heat subject.
Corrosion speed is to weigh the corrosion proof important indicator of material, and the corrosion rate of magnesium alloy is the main foundation of evaluating magnesium alloy corrosion resistance ability, also is indispensable data in the magnesium alloy Application Design.Therefore, mensuration magnesium alloy corrosion rate is significant.
Weight-loss method is to use at present the method for the most general mensuration magnesium alloy corrosion rate, is about to magnesium alloy sample and is soaked in the corrosive medium and takes out behind the certain hour, removes then that to measure sample behind the surface corrosion product weightless.Through sample weight loss rate Δ W (mg/cm
2/ day) convert annual corrosion rate P again to
W(mm/year):
P
W＝2.10ΔW (1)
Weight-loss method is generally considered to be corrosion rate evaluation means the most reliably.Usually be used as standard and weigh the reliability of other measuring methods.Yet there is following weak point in weight-loss method:
(1) weight-loss method can only record the average corrosion rate in the whole soak time, and can't monitor the instantaneous real-time corrosion speed in the immersion process, is not easy to understand the corrosion process of magnesium alloy.For example; If want to understand the situation of change of certain magnesium alloy corrosion rate with soak time; Can only adopt a plurality of samples to soak different time respectively; Can increase the experimental work amount greatly so on the one hand, experimental result also can receive the influence of sample individual difference on the other hand, and the experimental result reliability can be affected.
(2) owing to receive the restriction that corrosion causes the variation of weight, when measuring small etching extent, sensitivity is low.
(3) owing to need dispose corrosion product, in removing the corrosion product process, unavoidably can remove the magnesium metal that a part is not corroded, thereby the reliability of corrosion rate is calculated in influence with weight-loss method.
Summary of the invention
The present invention is in order to overcome weak point of the prior art; A kind of method of measuring magnesium or magnesium alloy corrosion rate is provided, can obtains average corrosion rate, can monitor instantaneous corrosion rate again simultaneously; The hydrogen rate of release changes into instantaneous corrosion rate in the magnesium alloy corrosion process through collecting and measuring; Can obtain more useful informations in the corrosion process, and, highly sensitive.
Another object of the present invention provides a kind of special-purpose experimental provision that is used to measure magnesium or magnesium alloy corrosion rate.
The present invention realizes through following technical proposals:
A kind of method of measuring magnesium or magnesium alloy corrosion rate; It is characterized in that, comprise the steps: the funnel back-off in the container that fills corrosive medium, magnesium metal or magnesium alloy sample to be hung on funnel inside; The funnel tail end is back-off one buret again, and the titration mouth of pipe is lower than the liquid level of corrosive medium; Buret inside is vacuumized and solution is drawn to the highest scale place of buret; Afterwards buret is sealed; The hydrogen that magnesium metal or magnesium alloy sample corrosion produce enters into the space on the buret meniscus with bubble form by funnel; Cause the liquid level in the buret to descend, the scale that descends through liquid level changes the amount V that draws sample per surface area, unit etching time generation hydrogen
H, the instantaneous corrosion rate P of calculating magnesium metal or magnesium alloy
H=2.279 V
HOr average corrosion rate P
AH=2.279V
THIn the formula: V
THBe the average precipitation rate of hydrogen.
The employed special-purpose experimental provision of the method for a kind of said determination magnesium or magnesium alloy corrosion rate; It is characterized in that; Be made up of buret, funnel and corrosive liquid container, being inverted in the said corrosive liquid container has funnel, and said funnel tail end back-off has buret; Sample is placed in the inverted funnel, and the titration mouth of pipe is lower than the liquid level of etchant solution in the beaker.
The present invention has following technique effect:
(1) method of the present invention can obtain the average corrosion rate of one section interior magnesium metal of corrosion soak time or magnesium alloy; Simultaneously can monitor instantaneous corrosion rate again; Can on a sample, record continuous etching extent and time relation curve, can obtain more useful informations in the corrosion process.
(2) the hydrogen rate of release obtains corrosion rate to method of the present invention in magnesium metal or the magnesium alloy corrosion process through collecting and measuring; Because the volume ratio of the magnesium metal release hydrogen of same etching extent is bigger; And the variation that causes weight is much relatively little; Therefore, measure same small etching extent, the sensitivity of weighing of amount gas ratio is higher.
(3) the method for the present invention influence that can not removed corrosion product through method that collect to measure release hydrogen, result of calculation is more reliable.
(4) the employed experimental provision of method of the present invention is simple in structure, can have no to collect all hydrogen that generated by the magnesium corrosion reaction with omitting, and is easy to use.
Description of drawings
Fig. 1 is used to measure the synoptic diagram of the special-purpose experimental provision of magnesium or magnesium alloy corrosion rate for the present invention;
The magnesium rate of metal corrosion that Fig. 2 records for method of the present invention is with the variation relation figure of etching time.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment the present invention is elaborated.
Fig. 1 is used to measure the synoptic diagram of the special-purpose experimental provision of magnesium or magnesium alloy corrosion rate for the present invention; Form by buret 1, funnel 2 and corrosive liquid container 4; Being inverted in the said corrosive liquid container 4 has funnel 2, and said funnel tail end back-off has buret 1, and sample 3 is placed in the inverted funnel; The titration mouth of pipe is lower than the liquid level of etchant solution in the corrosive liquid container, to realize hydraulic seal.The corrosive liquid container can use beaker.
The method of mensuration magnesium of the present invention or magnesium alloy corrosion rate comprises the steps: funnel 2 back-offs in the beaker that fills corrosive medium; Magnesium metal or magnesium alloy sample 3 usefulness fishing lines hang on funnel 2 inside; Funnel 2 tail ends are back-off one buret 1 again, and the titration mouth of pipe is lower than the liquid level of etchant solution in the beaker, according to the difference of sample corrosive nature; Buret can be selected different volumes, like 50ml or 100ml.With a pump bowl buret inside is vacuumized, and solution is drawn to the highest scale place of buret, afterwards, buret is sealed.The hydrogen that magnesium metal or magnesium alloy sample corrosion produce enters into the space on the buret meniscus with bubble form by funnel, and these hydrogen will displace the part solution in the buret and cause liquid level decline in the buret.The amount of the hydrogen of collecting just can directly be reflected by the scale variation through the decline degree of liquid level in the buret.In the experimentation, the volume through record corrosion soak time and collected hydrogen can simulate the hydrogen rate of release, thereby the speed of reflection magnesium sample corrosion promptly obtains momentary rate in the magnesium corrosion process with the situation of change of corrosion soak time.After experiment finished, the amount through the total release hydrogen of sample per surface area can also convert and obtain the average corrosion rate P in the whole soak time section
AH=2.279
VH, in the formula: V
THBe the average precipitation rate of hydrogen.
The principle that method of the present invention is measured the magnesium corrosion is following:
The net reaction of known magnesium corrosion is:
Mg+2H
2O＝Mg
2++2(OH)
-+H
2 (2)
Be magnesium atom of every dissolving, just have hydrogen molecule and produce that so just should be able to know the amount of the magnesium metal that is corroded through measuring the volume of separating out hydrogen in the corrosion process, the speed of being separated out by hydrogen just can be known the instantaneous velocity of magnesium metal erosion.Just, separate out the hydrogen (being equivalent to 22.4 liters under the standard conditions) of 1mol,, that is to say that separating out of every milliliter of hydrogen is equivalent to 1 milligram magnesium and is corroded and dissolved almost corresponding to the magnesium alloy of 22.3g, so weight loss rate Δ W (mg/Gm
2/ day) with hydrogen precipitation rate V
H(ml/Gm
2/ there is following relation between day):
ΔW＝1.085V
H (3)
This shows, can transform through hydrogen rate of release in collection and the mensuration magnesium alloy corrosion process and obtain magnesium metal weight loss rate, and then obtain magnesium corrosion momentary rate P
HWith formula (3) substitution formula (1):
P
H＝2.279V
H (4)
After collected hydrogen surpasses the buret volume, can utilize pump bowl again solution to be drawn to the highest scale of buret, continue to measure.To the magnesium sample of different corrosion resistances, also can select the buret of different thicknesses, to increase the susceptibility of institute's read data, what promptly corrosion speed was fast can select thick buret for use, and corrosion rate slow can select thin buret for use.
Embodiment 1
The funnel back-off in the container that fills 3.5%NaCl solution, is hung on funnel inside with the high-purity magnesium of as cast condition with a fishing line, and the funnel tail end is back-off one buret again, and the titration mouth of pipe is lower than the liquid level of etchant solution in the beaker.With a pump bowl buret inside is vacuumized; And solution is drawn to the highest scale place of buret; The hydrogen that the sample corrosion produces enters into the space on the buret meniscus with bubble form by funnel, and these hydrogen will displace the part solution in the buret and cause liquid level decline in the buret.
The corrosion soak time and the release hydrogen volume that write down in the experimentation are as shown in table 1.Specimen surface is long-pending to be 3.73cm
2, total corrosion soak time is 14 days, discharges total amount (21.7965ml/cm through sample per surface area hydrogen in the table 1
2) converting to obtain this section period (336.8/24=14 days) average corrosion rate P
AH=2.279V
TH=3.54mm/year.In addition, also can monitor the variation relation of corrosion rate with soak time, as shown in Figure 2.Can find out by figure; Significant change has taken place with corrosion soak time length in this high-purity magnesium sample corrosion rate, and at the immersion initial stage (I stage in like Fig. 2), corrosion rate very slowly; After soak time surpasses 24 hours; Corrosion rate is sharply accelerated (like the II stage among Fig. 2), and after soak time further extended to 170 hours, corrosion rate slowed down again (like the III stage among Fig. 2) to some extent.This shows, utilize the method can monitor some information in the magnesium metal erosion process, help research magnesium metal erosion mechanism.After experiment finishes, still can obtain this sample at this section average corrosion rate in the time through weight-loss method.Learn the sample weight loss rate through weighing
Δ W=1.723 (mg/cm
2/ day), can know P by formula (1) calculating
WBe 3.62mm/year, it is very identical that visible and the present invention measure the result that hydrogen separates out, thereby confirmed that also method of the present invention measures the reliability of magnesium rate of metal corrosion.
Table 1
Measure the reliability of magnesium rate of metal corrosion in order to verify method of the present invention; We utilize method of the present invention that a series of different magnesium test buttons (pure magnesium Mg, AZ91D and ZE41) are made an experiment, with utilizing hydrogen to separate out the average corrosion rate P that total obtains
HWith the average corrosion rate P that utilizes weight-loss method to obtain
WCompare, as shown in table 2.It is thus clear that the average corrosion rate that two kinds of methods obtain coincide very goodly, thereby verified that the method that the present invention measures the magnesium alloy corrosion rate has higher reliability.
Table 2
| The magnesium metal | P w(mm/year) | P H(mm/year) | P w/P H |
| Pure Mg | ?0.96 | ?1.0 | ?96％ |
| AZ91D | ?6.5 | ?7.1 | ?92％ |
| ZE41 | ?13.1 | ?14 | ?94％ |
Claims (2)
1. a method of measuring magnesium or magnesium alloy corrosion rate is characterized in that, comprises the steps:
The funnel back-off in the container that fills corrosive medium, is hung on funnel inside with magnesium metal or magnesium alloy sample, and the funnel tail end is back-off one buret again, and the titration mouth of pipe is lower than the liquid level of corrosive medium; Buret inside is vacuumized and solution is drawn to the highest scale place of buret; Afterwards buret is sealed; The hydrogen that magnesium metal or magnesium alloy sample corrosion produce enters into the space on the buret meniscus with bubble form by funnel; Cause the liquid level in the buret to descend, the scale that descends through liquid level changes the amount V that draws sample per surface area and unit etching time generation hydrogen
H, calculate the instantaneous corrosion rate P of magnesium metal or magnesium alloy then
H=2.279V
HOr average corrosion rate P
AH=2.279V
TH, in the formula: V
THBe the average precipitation rate of hydrogen.
2. the employed special-purpose experimental provision of method of described mensuration magnesium of claim 1 or magnesium alloy corrosion rate; It is characterized in that; Be made up of buret, funnel and corrosive liquid container, being inverted in the said corrosive liquid container has funnel, and said funnel tail end back-off has buret; Sample is placed in the inverted funnel, and the titration mouth of pipe is lower than the liquid level of etchant solution in the beaker.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105547980A (en) * | 2015-12-29 | 2016-05-04 | 东南大学 | Experimental device for simulating circulating bending load on material in flow field environment |
| CN107941684A (en) * | 2017-12-20 | 2018-04-20 | 佛山科学技术学院 | A kind of easy metal material corrosion resistance test infuser device |
| CN111781326A (en) * | 2020-06-24 | 2020-10-16 | 西安交通大学 | High-purity magnesium purity contrast detection method |
Citations (4)
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|---|---|---|---|---|
| SU1089499A1 (en) * | 1982-10-01 | 1984-04-30 | Всесоюзный Научно-Исследовательский Проектно-Конструкторский И Технологический Институт Источников Тока | Method of determination of quantity of active substance on accumulator electrode |
| US6301980B1 (en) * | 1998-12-18 | 2001-10-16 | Neil Munderloh | Titration apparatus using a syringe |
| CN101936829A (en) * | 2010-08-27 | 2011-01-05 | 华南理工大学 | Detachable gas collection measuring device for biodegradability of medical magnesium alloy |
| CN202421033U (en) * | 2011-12-28 | 2012-09-05 | 天津商业大学 | Special experimental device for determining corrosion rate of magnesium or magnesium alloys |
-
2011
- 2011-12-28 CN CN2011104477374A patent/CN102564932A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1089499A1 (en) * | 1982-10-01 | 1984-04-30 | Всесоюзный Научно-Исследовательский Проектно-Конструкторский И Технологический Институт Источников Тока | Method of determination of quantity of active substance on accumulator electrode |
| US6301980B1 (en) * | 1998-12-18 | 2001-10-16 | Neil Munderloh | Titration apparatus using a syringe |
| CN101936829A (en) * | 2010-08-27 | 2011-01-05 | 华南理工大学 | Detachable gas collection measuring device for biodegradability of medical magnesium alloy |
| CN202421033U (en) * | 2011-12-28 | 2012-09-05 | 天津商业大学 | Special experimental device for determining corrosion rate of magnesium or magnesium alloys |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105547980A (en) * | 2015-12-29 | 2016-05-04 | 东南大学 | Experimental device for simulating circulating bending load on material in flow field environment |
| CN105547980B (en) * | 2015-12-29 | 2018-08-28 | 东南大学 | A kind of simulation material is in flow fields environment by the experimental provision of reversed bending load |
| CN107941684A (en) * | 2017-12-20 | 2018-04-20 | 佛山科学技术学院 | A kind of easy metal material corrosion resistance test infuser device |
| CN111781326A (en) * | 2020-06-24 | 2020-10-16 | 西安交通大学 | High-purity magnesium purity contrast detection method |
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