CN103901082B - Tin plate sheet surface chromium amount electrolysis self-operated measuring unit and mensuration endpoint method - Google Patents
Tin plate sheet surface chromium amount electrolysis self-operated measuring unit and mensuration endpoint method Download PDFInfo
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Abstract
A kind of tin plate sheet surface chromium amount electrolysis self-operated measuring unit and mensuration endpoint method, belong to analysis field.It includes computer, digitial controller, two-way constant current supply, two-sided electrolysis bath, sample closing means and liquid feeding system；The I/O end of its computer is connected with the control end of digitial controller and two-way constant current supply, the control end of the outfan of digitial controller and sample closing means and liquid feeding system is connected respectively, the outfan of two-way constant current supply is connected respectively with each electrode in two-sided electrolysis bath, and each electrolyte pipeline of liquid feeding system and two-sided electrolysis bath is connected respectively.Present invention also offers the surface chromium electrolysis endpoint method of above-mentioned self-operated measuring unit.It adopts double; two cell construction, it is achieved that the tow sides of sample automatically measure, and improves the precision that tin plate sheet surface chromium electrolysis is measured.Can be widely used for the detection field of tin plate product surface chromium.
Description
Technical field
The invention belongs to the field of electrochemically test or analysis of material, particularly relate to a kind of determinator for electrotinning product surface chromium amount and assay method.
Background technology
Electrotinning product typically requires through Passivation Treatment, to improve its product decay resistance；The difference of passivation mode and passivation amount, directly affect the performances such as the corrosion resistance of tin plate, resistance to SO_2 and covering with paint property, therefore rapid and accurate determination through the content of the chromium of the tin plate sheet surface of Passivation Treatment (in the industry traditionally referred to as chromium amount, lower same), for improving technology controlling and process level and ensureing that product quality has great importance.
The existing assay method to the chromium amount of tin plate sheet surface has chemical method (such as: spectrophotography, atomic absorption method, plasma spectroscopy), X-fluorescence method (can be CN102411011A referring to application publication number, Shen Qing Publication day is on April 11st, 2012, and name is called the related content in the Chinese invention patent application of " rapid assay methods of tin plate sheet surface chromium amount ") and electrolysis etc..
In above-mentioned analysis method, chemical method with alkali or acid-soluble solution surface chromium, need to adopt the chromium amount in spectrophotometry solution, and chemical method accuracy is high, but complicated operation, minute is long.X-fluorescence method needs the content of chromium in deduction substrate when measuring tin plate sheet surface chromium, owing to surface chromium content is low, the method accuracy of detection is relatively low.And electrolysis is in phosphate buffered solution, sample is as anode, by adopting constant current, makes the surface chromium oxidation of sample, according to tin plate sheet surface chromium electrolysis time, and the calibration factor K gauging surface chromium amount of tin plate sheet surface chromium electrolysis and chemical method.
GB GB/T18290-2012 " test method of ferrostan surface chromium amount ", the document such as International Tin Research Institute " tin plate guide " and " taggers tin and sheet iron of wuxi " gives tin plate sheet surface chromium amount electrolytic measurement method and schematic diagram of device.Owing to these documents provide electrolysis endpoint method difference, cause that tin plate sheet surface chromium measurements is also variant；Document provides the device of measurement simultaneously is sample single face manual measurement device, and these device complicated operations, the reliability and stability of device are relatively difficult to ensure card.
Notification number is CN201159727Y, the day for announcing is in December, 2008 Chinese utility model patent of 3 days, disclose " a kind of electrolysis unit for tin plate detection ", this electrolysis unit includes body, body one side end face has sample aperture, body interior is provided with electrolyte cavity volume, and be connected with sample aperture, electrolyte cavity volume side is provided with reference electrode reference electrode plug, a pyramidal projections it is provided with in electrolyte cavity volume, pyramidal projections outer wall is provided with auxiliary electrode, and inside has through hole, and is connected with electrolyte cavity volume, reference electrode reference electrode plug respectively；Bodies top also has passage and inlet opening.This electrolysis unit simple in construction, easy to use, it is possible to be respectively used to the coating of tin plate and the detection of the multinomial performance of various skin covering of the surface.But this patent only proposes the design of the single electrolysis unit with tapered electrode, be still manual measurement mode, and unrealized two-sided while automatic measurement function.
Tin plate sheet surface chromium electrolysis assay method is that the oxidizing potential according to chromium measures tin plate sheet surface chromium amount, for various processes unit, the anodization potentials of chromium has some differences, with chemical method, the measured value of tin plate sheet surface chromium amount electrolysis need to be demarcated, for same process unit, it is possible to adopt the calibration factor K of same tin plate sheet surface chromium electrolysis to carry out the mensuration of surface chromium amount.
Electrolysis stripping terminal for tin plate sheet surface chromium (is accustomed in the industry being referred to as to measure terminal, lower same), there are two kinds of determination methods at present, first method is GB GB/T18290-2012 " test method of ferrostan surface chromium amount ", the method is that the 1st cusp A lights from electrolytic curve, current potential rising 200mV is as the electrolysis stripping terminal B point of tin plate sheet surface chromium, from A point (t0, sec) to B point (t1, sec) required time (Δ T1=t1-t0, sec) for the time needed for the chromium electrolysis stripping of surface, it is easy that the method peels off endpoint, instrument easily realizes automatization.Second method is method " tin plate the guide " (International Tin Research Institute that International Tin Research Institute provides, Zhou Qiliang translates), the method is to be that the starting point C of obvious line relationship is as tin plate sheet surface chromium electrolysis stripping terminal to curve from the 1st cusp A, from A point (t0, sec) to C point (t2, sec) required time (Δ T2=t2-t0, sec) is the time needed for the chromium electrolysis stripping of surface, as shown in Figure 1.Difference due to conditions such as production technology and tin plate storage conditions, the result that 200mv method of addition and straight line starting point method both endpoint methods are measured can be made to have larger difference, and this can make user that most suitable endpoint method cannot be used to obtain reliable measurement result.
Summary of the invention
The technical problem to be solved is to provide a kind of tin plate sheet surface chromium amount electrolysis self-operated measuring unit and measures endpoint method, it adopts double; two cell construction, sample clamping is enclosed between double; two electrolysis bath, the positive and negative two sides achieving sample automatically measures, there is the functions such as sample self-closed, liquid feeding, measurement and data process, the advantage combining existing chemical method and electrolysis, adopt automatization, digitizing technique and measuring technology, improve the precision that tin plate sheet surface chromium electrolysis is measured.
The technical scheme is that and provide described self-operated measuring unit to include computer, digitial controller, two-way constant current supply, two-sided electrolysis bath, sample closing means and liquid feeding system；
The I/O end of its described computer is connected with the control end of digitial controller and two-way constant current supply, the control end of the outfan of described digitial controller and sample closing means and liquid feeding system is connected respectively, the outfan of described two-way constant current supply is connected respectively with each electrode in two-sided electrolysis bath, and each electrolyte pipeline of described liquid feeding system and two-sided electrolysis bath is connected respectively.
Wherein, described two-sided electrolysis bath is the monomer electrolysis bath that two openings are oppositely arranged, and the first monomer electrolysis bath therein is fixed on pedestal, and second comonomer electrolysis bath is connected with sample closing means；When performing automatically to test, under the driving of sample closing means, second comonomer electrolysis bath moves to the first monomer electrolysis bath, the opening of second comonomer electrolysis bath and the opening close contact of the first monomer electrolysis bath, will be located in the sample between first, second monomer electrolysis bath opening and be enclosed between first, second monomer electrolysis bath opening；After test terminates automatically, under the driving of sample closing means, second comonomer electrolysis bath leaves the first monomer electrolysis bath, in order to is enclosed in the sample between first, second monomer electrolysis bath opening and takes out.
Described self-operated measuring unit is when performing automatically to test, computer sends instruction, digitial controller controls sample closing means chronologically and drives the second comonomer electrolysis bath in two-sided electrolysis bath to shift to the first monomer electrolysis bath, first, the opening close contact of second comonomer electrolysis bath, sample is closed, liquid feeding system adds electrolyte by the road in two-sided electrolysis bath, two-way constant current supply is started working, and by the characteristic value transmission of tin plate sheet surface chromium electrolysis reaction to computer, when electrolysis stripping to current potential u does not occur significantly to change, measurement is automatically stopped, sample closing means resets, second comonomer electrolysis bath in two-sided electrolysis bath leaves the first monomer electrolysis bath, sample releases to be closed, whole measurement process terminates.
Described self-operated measuring unit passes through two-sided electrolysis bath grip seal sample, adopt two-way constant current supply the obverse and reverse of sample to be carried out electrolysis electrolysis stripping simultaneously, by in the characteristic value transmission of the surface chromium electrolysis reaction on positive and negative for tin plate two sides to computer, automatically measure, obtain the electrolytic curve on positive and negative two sides simultaneously.
Concrete, its described computer is PC, for controlling the startup of digitial controller and the setting of two-way constant current supply running parameter, in automatic measurement process, and the characteristic value of the electrolysis reaction in described computer real-time acquisition measurement process；After measurement process terminates, described computer is automatically into data processor, obtain the corresponding potential value u of t on electrolytic curve, obtain the electrolysis time Δ T of tin plate sheet surface chromium according to surface chromium electrolysis endpoint method, obtain the surface chromium amount of tin plate according to the calibration factor K of surface chromium electrolysis.
Concrete, its described digitial controller is time schedule controller, in automatic measurement process, sample is closed by described digitial controller sequential control sample closing means chronologically, liquid feeding system adds electrolyte in two-sided electrolysis bath, controlling liquid feeding system and add the liquid feeding time of electrolyte in two-sided electrolysis bath, after measurement process terminates, described digitial controller controls sample closing means and resets.
Concrete, its described two-way constant current supply is two-sided digital formula constant current supply, for providing required constant current source for the reaction of two-sided electrolytic tank electrolysis, and to the characteristic value of its detected every electrolysis reaction of computer export.
Concrete, its described two-sided electrolysis bath includes the monomer electrolysis bath that two openings are oppositely arranged, each monomer electrolysis bath inner chamber is respectively arranged with a cone, is wrapped platinum wire as working electrode, the negative pole that its working electrode reacts as tin plate sheet surface chromium electrolysis at cone surface；Arrange a spring stylus to contact with sample through the first monomer electrolysis bath A, constitute sample electrode, in this, as the positive pole of electrolysis reaction；Each monomer electrolysis bath is additionally provided with reference electrode, as the zero potential of output current potential；Vertebral body in its described first, second monomer electrolysis bath inner chamber is oppositely arranged；In the upper end of described first, second monomer electrolysis bath, it is respectively arranged with the connection corresponding to liquid feeding system by the road of filling opening and overfall, described filling opening and overfall；Its first described monomer electrolysis bath is fixed on substrate；Described second comonomer electrolysis bath is connected with the push rod of sample closing means；When the push rod of sample closing means moves forward, drive the opening of second comonomer electrolysis bath and the opening close contact of the first monomer electrolysis bath, by sample clamping between the first monomer electrolysis bath and the opening of second comonomer electrolysis bath, reach the purpose that sample is closed.
Further, opening at described first, second monomer electrolysis bath, it is respectively arranged with first, second sealing ring, when the push rod of sample closing means moves forward and puts in place, second sealing ring of described second comonomer electrolysis bath opening and the first sealing ring close contact of the first monomer electrolysis bath opening, by sample clamping between first, second sealing ring of first, second monomer electrolysis bath opening, reach the purpose that sample seals.
Further, described sample closing means is the pneumatic type hydraulic cylinder with push rod, when the electromagnetic valve in source of the gas gas circuit is opened, compression air enters cylinder, promotion push rod travels forward, drive second comonomer electrolysis bath to move forward and be in close contact with the first monomer electrolysis bath, reaching the purpose that sample is closed；Working as closed electromagnetic valve, push rod is retracted backward, drives second comonomer electrolysis bath to reset, and two-sided electrolysis bath is opened；The action sequence of its described sample closing means is controlled by digitial controller, and user can be set at computer.
Concrete, its described liquid feeding system includes fluid filling pump, liquid-feeding tube, overflow pipe, seal cup and reagent barrel, fluid filling pump adds electrolyte by liquid-feeding tube to two-sided electrolysis bath, unnecessary electrolyte is spilled over to seal cup from overflow pipe, and it is back in reagent barrel, to guarantee in the inner chamber that electrolyte is completely filled with two-sided electrolysis bath；After tin plate sheet surface chromium electrolysis terminates, two-sided electrolysis bath is opened, and the electrolyte in two-sided electrolysis bath inner chamber is back in reagent barrel by seal cup；The liquid feeding time of its described electrolyte was controlled by the operation time of fluid filling pump, and the operation time of described fluid filling pump is controlled by digitial controller, and user can be set at computer.
Further, the characteristic value of described electrolysis reaction at least includes electric current i, current potential u and the electrolysis time t of electrolysis reaction.
Present invention also offers the measuring method of a kind of above-mentioned tin plate sheet surface chromium amount electrolysis self-operated measuring unit, it is characterized in that tin plate sheet surface chromium amount is carried out automatically measuring according to the following step by described self-operated measuring unit:
Sample is put in two-sided electrolysis bath, computer sends instruction to digitial controller, the push rod of sample closing means moves forward, two-sided electrolysis bath closes, sample is closed, liquid feeding system adds electrolyte in two-sided electrolysis bath, now digitial controller triggering two-way digital constant-current source is started working, the electric current i of computer acquisition electrolysis reaction, the characteristic values such as current potential u and time t, when electrolysis stripping to current potential u does not occur significantly to change, measurement is automatically stopped, sample closing means resets, two-sided electrolysis bath is opened, electrolyte discharges to reagent barrel, take out sample, computer is automatically into data processor, mobile mouse obtains the corresponding potential value u of t on electrolytic curve, the electrolysis time Δ T of tin plate sheet surface chromium is obtained according to surface chromium electrolysis endpoint rule, calibration factor K according to surface chromium electrolysis obtains the surface chromium amount of tin plate.
Invention further provides a kind of surface chromium electrolysis endpoint method of above-mentioned tin plate sheet surface chromium amount electrolysis self-operated measuring unit, including the acquisition of electrolytic curve, it is characterized in that:
Tin plate sheet surface chromium amount electrolytic curve finds change in voltage starting point A point moment t0；
Finding increment 200mvB point moment t1 and A point to B point required time Δ T1, curve linearly section starting point C point moment t2 and A point is to C point required time Δ T2；
When B point t1 and C puts the absolute value≤threshold value d of t2 two Time of day offsets, its corresponding B point or C point are that surface chromium electrolysis peels off terminal, and its corresponding time Δ T1 or Δ T2 is as the electrolysis stripping time Δ T of surface chromium；
When B point t1 and C puts the absolute value > threshold value d of t2 two Time of day offsets, cut-off line starting point C point t2 is the electrolysis stripping terminal of surface chromium, and its corresponding time Δ T2 is as electrolysis stripping time Δ T；
To measuring the unconspicuous sample of straight line starting point, adopting 200mv increment endpoint determination Δ T1 as surface chromium electrolysis stripping time Δ T, now accurately measuring of tin plate sheet surface chromium needs to adopt chemical method measurement carry out and obtain.
Its described A point is to B point required time Δ T1=t1-t0, and unit is the second；Described A point is to C point required time Δ T2=t2-t0, and unit is the second.
Its described electrolysis measures endpoint method and measures allowable error according to tin plate sheet surface chromium amount test chamber, formulates 200mV increment and judges that end-point method t1 and straight line starting point judge time difference threshold value d between end-point method t2.
Further, its described threshold value d determines according to following relationship:
Threshold value d=│ t2-t1 │=mensuration allowable error D ÷ calibration factor K；
Wherein, t1 is the increment 200mvB point moment, and unit is the second；T2 is the curve linearly section starting point C point moment, and unit is the second；Measure allowable error D and formulated according to technological requirement by detecting department and user；The conversion coefficient of the electrolysis that calibration factor K is tin plate sheet surface chromium electrolysis to be obtained with chemical method correlation curve and chemical method, the i.e. calibration factor of tin plate sheet surface chromium electrolysis and chemical method.
Compared with the prior art, the invention have the advantage that
1. adopt double; two cell construction, sample clamping is enclosed between double; two electrolysis bath, the positive and negative two sides achieving sample automatically measures, easy and simple to handle, automaticity is high, only need to putting in electrolysis bath by sample, determinator just can be automatically performed the processes such as the stripping of sample electrolysis method, electrolysis measurement, data process；
2. measuring speed is fast, and measuring a sample only needs 5 minutes, and the common chemical method measurement cycle is 120 minutes, substantially increases working performance；
3. certainty of measurement is high, and the advantage combining existing chemical method and electrolysis, in conjunction with two kinds of electrolytic measurement methods, gives tin plate sheet surface chromium electrolysis endpoint method, makes electrolysis certainty of measurement be improved.
Accompanying drawing explanation
Fig. 1 is existing tin plate sheet surface chromium electrolysis experiment curv schematic diagram；
The system that Fig. 2 is tin plate sheet surface chromium electrolysis self-operated measuring unit of the present invention constitutes schematic diagram；
Fig. 3 is the structural representation of tin plate sheet surface chromium electrolysis self-operated measuring unit of the present invention；
Fig. 4 is the structural representation of two-sided electrolysis bath；
Fig. 5 is the structural representation of sample closing means；
Fig. 6 be 200mv method of addition endpoint determination consistent with straight line starting point endpoint determination time tin plate sheet surface chromium amount self-operated measuring unit electrolytic curve；
The electrolytic curve of tin plate sheet surface chromium amount self-operated measuring unit when Fig. 7 is to adopt 200mv increment endpoint determination；
The electrolytic curve of tin plate sheet surface chromium amount self-operated measuring unit when Fig. 8 is to adopt straight line starting point endpoint determination；
Fig. 9 is the block flowsheet schematic diagram that tin plate sheet surface chromium electrolysis of the present invention measures endpoint method；
Figure 10 is that present invention application tin plate sheet surface chromium electrolysis measures endpoint method and self-operated measuring unit and the chemical method correlation analysis schematic diagram to 1420 tin plate sheet surface chromium mark feed.
In figure, 1 is computer, and 2 is digitial controller, and 3 is two-way constant current supply, and 4 is two-sided electrolysis bath, 4-1 is sealing ring, and 4-2 is sample electrode, and 4-3 is working electrode, and 4-4 is reference electrode, 5 is sample closing means, and 5-1 is push rod, and 5-2 is cylinder, and 5-3 is electromagnetic valve, 6 is liquid feeding system, and 6-1 is fluid filling pump, and 6-2 is liquid-feeding tube, 6-3 is overflow pipe, and 6-4 is seal cup, and 7 is reagent barrel, 8 is sample, and 4-A is the first monomer electrolysis bath, and 4-B is second comonomer electroplating bath.
Detailed description of the invention
Below in conjunction with accompanying drawing, the present invention will be further described.
In Fig. 1, the electrolysis of tin plate sheet surface chromium peels off terminal two kinds of determination methods, first method is GB GB/T18290-2012 " test method of ferrostan surface chromium amount ", the method is that the 1st cusp A lights from electrolytic curve, current potential rising 200mV is as the electrolysis stripping terminal B point of tin plate sheet surface chromium, from A point (t0, sec) to B point (t1, sec) required time (Δ T1=t1-t0, sec) for the time needed for the chromium electrolysis stripping of surface, it is easy that the method peels off endpoint, and instrument easily realizes automatization；Second method is method " tin plate the guide " (International Tin Research Institute that International Tin Research Institute provides, Zhou Qiliang translates), the method is to be that the starting point C of obvious line relationship is as tin plate sheet surface chromium electrolysis stripping terminal to curve from the 1st cusp A, from A point (t0, sec) to C point (t2, sec) required time (Δ T2=t2-t0, sec) is the time needed for the chromium electrolysis stripping of surface.
In Fig. 2, the tin plate sheet surface chromium amount electrolysis apparatus for automatically measuring of the present invention, it is made up of computer 1, digitial controller 2, two-way constant current supply 3, two-sided electrolysis bath 4, sample closing means 5 and liquid feeding system 6 etc..
The I/O end of its described computer is connected with the control end of digitial controller and two-way constant current supply, the control end of the outfan of described digitial controller and sample closing means and liquid feeding system is connected respectively, the outfan of described two-way constant current supply is connected respectively with each electrode in two-sided electrolysis bath, and each electrolyte pipeline of described liquid feeding system and two-sided electrolysis bath is connected respectively.
In Fig. 3, computer 1 sends instruction, digitial controller 2 controls sample closing means 5 chronologically and is closed by sample, liquid feeding system 6 adds electrolyte to two-sided electrolysis bath 4, two-way constant current supply 3 is started working, and characteristic value (electric current i, current potential u, time t etc.) transmission tin plate sheet surface chromium electrolysis reacted is to computer 1, terminates measuring when significantly change does not occur the current potential of computer acquisition, sample closing means 5 resets, and whole measurement terminates.
Wherein, described computer is PC, for controlling the startup of digitial controller and the setting of two-way constant current supply running parameter, in automatic measurement process, and the characteristic value of the electrolysis reaction in described computer real-time acquisition measurement process；After measurement process terminates, described computer is automatically into data processor, obtain the corresponding potential value u of t on electrolytic curve, obtain the electrolysis time Δ T of tin plate sheet surface chromium according to surface chromium electrolysis endpoint method, obtain the surface chromium amount of tin plate according to the calibration factor K of surface chromium electrolysis.
Described digitial controller is time schedule controller, in automatic measurement process, sample is closed by described digitial controller sequential control sample closing means chronologically, liquid feeding system adds electrolyte in two-sided electrolysis bath, control liquid feeding system in two-sided electrolysis bath, add the liquid feeding time of electrolyte, after measurement process terminates, described digitial controller controls sample closing means and resets.
Described two-way constant current supply is two-sided digital formula constant current supply, it has the functions such as two-way numeral input simultaneously, numeral output, for providing required constant current source for the reaction of two-sided electrolytic tank electrolysis, and to the characteristic value of its detected every electrolysis reaction of computer export.When reality is measured, require that carrying out electrolysis at computer measures parameter setting according to tin plate sheet surface chromium electrolytic measurement, control two-way constant-current source by computer to start working, electrolysis response characteristic value (electric current i, voltage u, electrolysis time t) etc. in computer real-time acquisition measurement process.
In Fig. 4, described two-sided electrolysis bath includes the monomer electrolysis bath that two openings are oppositely arranged, each monomer electrolysis bath inner chamber is respectively arranged with a cone, is wrapped platinum wire as working electrode, the negative pole that its working electrode 4-3 reacts as tin plate sheet surface chromium electrolysis at cone surface.
The cone structure design of monomer electrolysis bath inner chamber, it is possible to make tin plate sheet surface chromium electrolysis electric current density spread to outer in the middle part of sample, effectively prevent the current polarizing of sample, improve electric current density.
Arrange a spring stylus to contact with sample through the first monomer electrolysis bath 4-A, constitute sample electrode 4-2, in this, as the positive pole of electrolysis reaction；Each monomer electrolysis bath is additionally provided with reference electrode 4-4, as the zero potential of output current potential；Vertebral body in its described first, second monomer electrolysis bath inner chamber is oppositely arranged；In the upper end of described first, second monomer electrolysis bath, being respectively arranged with filling opening 6-2 and overfall 6-3, described filling opening and overfall are corresponding with liquid feeding system (representing with fluid filling pump code name 6-1 in figure) by the road to be connected.
Its first described monomer electrolysis bath is fixed on substrate；Described second comonomer electrolysis bath is connected with the push rod of sample closing means 5；When the push rod of sample closing means moves forward, drive the opening of second comonomer electrolysis bath and the opening close contact of the first monomer electrolysis bath, by sample clamping between the first monomer electrolysis bath and the opening of second comonomer electrolysis bath, reach the purpose that sample is closed.
Opening at described first, second monomer electrolysis bath, it is respectively arranged with first, second sealing ring (representing the first sealing ring with code name 4-1 in figure), when the push rod of sample closing means moves forward and puts in place, second sealing ring of described second comonomer electrolysis bath opening and the first sealing ring close contact of the first monomer electrolysis bath opening, by sample clamping between first, second sealing ring of first, second monomer electrolysis bath opening, reach the purpose that sample seals.
Liquid feeding system 6 is made up of fluid filling pump 6-1, liquid-feeding tube 6-2, overflow pipe 6-3, seal cup 6-4 etc., fluid filling pump 6-1 adds electrolyte from reagent barrel 7 to two-sided electrolysis bath 4 by liquid-feeding tube 6-2, unnecessary electrolyte is spilled over to seal cup 6-4 from overflow pipe 6-3 and is back in reagent barrel 7, so may insure that electrolyte is completely filled with in two-sided electrolysis bath 4；After tin plate sheet surface chromium electrolysis terminates, two-sided electrolysis bath 4 is opened, and in two-sided electrolysis bath 4, electrolyte is back in reagent barrel 7 by seal cup 6-4.The liquid feeding time (being actually the operation time of fluid filling pump) of electrolyte is controlled by digitial controller 2, and user can be set at computer.
In Fig. 5, sample closing means 5 is the pneumatic type hydraulic cylinder 5-2 with push rod 5-1, when the electromagnetic valve 5-3 in source of the gas gas circuit opens, compression air enters cylinder, promotion push rod travels forward, drive second comonomer electrolysis bath 4-B to move forward and be in close contact with the first monomer electrolysis bath, reaching the purpose that sample is closed.
Working as closed electromagnetic valve, push rod is retracted backward, drives second comonomer electrolysis bath to reset, and two-sided electrolysis bath is opened.
The action sequence of sample closing means is controlled by digitial controller, and user can be set at computer.
Fig. 6 is sample 1 surface chromium electrolytic curve, adopts the situation that 200mV increment endpoint determination is consistent with straight line starting point endpoint determination；Fig. 7 and Fig. 8 is sample 2 electrolytic curve, adopts the situation that 200mV method of addition end-point method and straight line starting point endpoint determination are inconsistent, and wherein Fig. 7 is that sample 2 adopts 200mV method of addition endpoint method, and Fig. 8 is that sample 2 adopts straight line starting point endpoint method.
Concrete, Fig. 6 be 200mv method of addition endpoint determination (GB GB/T18290-2012 " test method of ferrostan surface chromium amount ") consistent with straight line starting point endpoint determination (International Tin Research Institute offer method) time situation, the measured value that both approaches obtains and chemical method measured value coincide.
Fig. 7 is 200mv increment endpoint determination (GB GB/T18290-2012 " test method of ferrostan surface chromium amount ") and the straight line starting point endpoint determination (International Tin Research Institute offer method) situation time inconsistent.It adopts 200mv increment endpoint determination, and its measured value and chemical determination value error reach more than 40%.
Fig. 8 is 200mv method of addition endpoint determination (GB GB/T18290-2012 " test method of ferrostan surface chromium amount ") and the straight line starting point endpoint determination (International Tin Research Institute offer method) situation time inconsistent.It adopts straight line starting point endpoint determination, and its measured value coincide with chemical method measured value.
The electrolysis of sample 1 and sample 2 is as shown in table 1 with the contrast of chemical method measured value: sample 1 adopts 200mV method of addition endpoint method and straight line starting point endpoint method, and its measured value coincide with chemical method measured value；Sample 2 adopts 200mV method of addition endpoint method lower than chemical method measured value, adopts straight line starting point endpoint method consistent with chemical method measured value with measured value.
Table 1, tin plate sheet surface chromium measurement Comparative result
The present invention is directed to two kinds of commonly used at present surface chromium amount electrolysis measuring methods to study.Due to differences such as Tinplate Production technique and storage conditions, the electrolyte properties of tin plate sheet surface chromium is also different, causes that tin plate sheet surface chromium electrolytic curve in electrolytic process is different, it is therefore necessary to comprehensive two kinds of methods just can obtain test result accurately and reliably.
Allowable error is measured according to tin plate sheet surface chromium amount test chamber, formulating 200mV increment and judge that end-point method t1 (sec) and straight line starting point judge time difference threshold value d between end-point method t2 (sec), its threshold value d mathematical relationship is: threshold value d=│ t2-t1 │=mensuration allowable error D ÷ calibration factor K；Being 3sec for applicant's unit 1420 electrotinning surface chromium electrolysis t2 (sec) and t1 (sec) time difference threshold value d, now 200mV method of addition judges that terminal and straight line starting point method judge that the error of terminal is 0.22mg/m2, (electric current density is 50uA/cm2).
In Fig. 9, block diagram is given to the tin plate sheet surface chromium amount electrolysis endpoint method of the present invention, it is specifically described as follows: in tin plate sheet surface chromium amount electrolytic curve, find change in voltage starting point A point moment (t0, sec), then find increment 200mvB point moment (t1, sec) and A point to B point required time Δ T1 (Δ T1=t1-t0) sec；Curve linearly section starting point C point moment (t2, sec) and A point are to C point required time Δ T2 (Δ T2=t2-t0) sec.As B point (t1, sec) with C point (t2, during absolute value≤threshold value the d of sec) two Time of day offsets, its corresponding B point or C point are surface chromium electrolysis stripping terminal, its correspondence time Δ T1 (sec) or Δ T2 (sec) the electrolysis stripping time Δ T as surface chromium；When the absolute value of B point (t1, sec) and C point (t2, sec) two Time of day offsets surpasses > threshold value d time, cut-off line starting point C point t2(t2, sec) for the electrolysis stripping terminal of surface chromium, its correspondence time Δ T2 (sec) is as electrolysis stripping time Δ T；Measuring the unconspicuous sample of straight line starting point for some electrolysis can adopt 200mv increment endpoint determination Δ T1 (sec) as surface chromium electrolysis stripping time Δ T, now the certainty of measurement of tin plate sheet surface chromium is difficult to ensure that, accurately measures and needs to adopt chemical method to measure.
In Figure 10, adopt the tin plate sheet surface chromium amount electrolysis of chemical method and the present invention in GB GB/T18290-2012 " test method of ferrostan surface chromium amount " to measure endpoint rule and tin plate sheet surface chromium amount that Baosteel 1420 Electroplating Tin Set is produced by self-operated measuring unit is measured respectively, obtain the calibration curve of tin plate sheet surface chromium amount electrolysis, 11 replications of tow sides surface chromium amount are carried out respectively by the tin plate that 1420 tin plating units are produced, its relative standard deviation respectively 3.29% and 4.02%, electrolysis is measured and the correlation coefficient γ of chemical method in GB GB/T18290-2012 " test method of ferrostan surface chromium amount "2=0.9961(pendulous frequency N=92), there is good dependency, accuracy of detection meets actual production requirement.
The present invention adopts double; two cell construction, sample clamping is enclosed between double; two electrolysis bath, the positive and negative two sides achieving sample automatically measures, and has the functions such as sample self-closed, liquid feeding, measurement and data process, its certainty of measurement Pass Test room measuring accuracy requirement；The reliability of assay device, stability have been satisfied by the requirement of Site Detection, improve the precision that tin plate sheet surface chromium electrolysis is measured.
The present invention combines the advantage of existing chemical method and electrolysis, in conjunction with two kinds of electrolytic measurement methods, gives tin plate sheet surface chromium electrolysis endpoint method, electrolysis certainty of measurement is made to be improved, measuring speed greatly speeds up, and measuring a sample only needs 5 minutes, substantially increases working performance.
The method can be widely used in the detection field of tin plate product surface chromium.
Claims (10)
1. a tin plate sheet surface chromium amount electrolysis self-operated measuring unit, including computer, constant current supply, electrolysis bath, sample enclosed construction and liquid feeding system；It is characterized in that:
Described self-operated measuring unit also includes digitial controller, two-way constant current supply, two-sided electrolysis bath, sample closing means and liquid feeding system；
The I/O end of its described computer is connected with the control end of digitial controller and two-way constant current supply, the control end of the outfan of described digitial controller and sample closing means and liquid feeding system is connected respectively, the outfan of described two-way constant current supply is connected respectively with each electrode in two-sided electrolysis bath, and each electrolyte pipeline of described liquid feeding system and two-sided electrolysis bath is connected respectively；
Wherein, described two-sided electrolysis bath is the monomer electrolysis bath that two openings are oppositely arranged, and the first monomer electrolysis bath therein is fixed on pedestal, and second comonomer electrolysis bath is connected with sample closing means；When performing automatically to test, under the driving of sample closing means, second comonomer electrolysis bath moves to the first monomer electrolysis bath, the opening of second comonomer electrolysis bath and the opening close contact of the first monomer electrolysis bath, will be located in the sample between first, second monomer electrolysis bath opening and be enclosed between first, second monomer electrolysis bath opening；After test terminates automatically, under the driving of sample closing means, second comonomer electrolysis bath leaves the first monomer electrolysis bath, in order to is enclosed in the sample between first, second monomer electrolysis bath opening and takes out；
Described two-way constant current supply is two-sided digital formula constant current supply, for providing required constant current source for the reaction of two-sided electrolytic tank electrolysis, and to the characteristic value of its detected every electrolysis reaction of computer export；
Described two-sided electrolysis bath includes the monomer electrolysis bath that two openings are oppositely arranged, each monomer electrolysis bath inner chamber is respectively arranged with a cone, it is wrapped platinum wire as working electrode, the negative pole that its working electrode reacts as tin plate sheet surface chromium electrolysis at cone surface；Arrange a spring stylus to contact with sample through the first monomer electrolysis bath A, constitute sample electrode, in this, as the positive pole of electrolysis reaction；Each monomer electrolysis bath is additionally provided with reference electrode, as the zero potential of output current potential；Vertebral body in its described first, second monomer electrolysis bath inner chamber is oppositely arranged；In the upper end of described first, second monomer electrolysis bath, it is respectively arranged with the connection corresponding to liquid feeding system by the road of filling opening and overfall, described filling opening and overfall；Its first described monomer electrolysis bath is fixed on substrate；Described second comonomer electrolysis bath is connected with the push rod of sample closing means；When the push rod of sample closing means moves forward, drive the opening of second comonomer electrolysis bath and the opening close contact of the first monomer electrolysis bath, by sample clamping between the first monomer electrolysis bath and the opening of second comonomer electrolysis bath, reach the purpose that sample is closed；
Described sample closing means is the pneumatic type hydraulic cylinder with push rod, when the electromagnetic valve in source of the gas gas circuit is opened, compression air enters cylinder, promotes push rod to travel forward, drive second comonomer electrolysis bath to move forward and be in close contact with the first monomer electrolysis bath, reaching the purpose that sample is closed；Working as closed electromagnetic valve, push rod is retracted backward, drives second comonomer electrolysis bath to reset, and two-sided electrolysis bath is opened；The action sequence of its described sample closing means is controlled by digitial controller, and user can be set at computer；
Described self-operated measuring unit is when performing automatically to test, computer sends instruction, digitial controller controls sample closing means chronologically and drives the second comonomer electrolysis bath in two-sided electrolysis bath to shift to the first monomer electrolysis bath, first, the opening close contact of second comonomer electrolysis bath, sample is closed, liquid feeding system adds electrolyte by the road in two-sided electrolysis bath, two-way constant current supply is started working, and by the characteristic value transmission of tin plate sheet surface chromium electrolysis reaction to computer, when electrolysis stripping to current potential u does not occur significantly to change, measurement is automatically stopped, sample closing means resets, second comonomer electrolysis bath in two-sided electrolysis bath leaves the first monomer electrolysis bath, sample releases to be closed, whole measurement process terminates；
The characteristic value of described electrolysis reaction at least includes electric current i, current potential u and the electrolysis time t of electrolysis reaction；
Described self-operated measuring unit passes through two-sided electrolysis bath grip seal sample, adopt two-way constant current supply the obverse and reverse of sample to be carried out electrolysis electrolysis stripping simultaneously, by in the characteristic value transmission of the surface chromium electrolysis reaction on positive and negative for tin plate two sides to computer, automatically measure, obtain the electrolytic curve on positive and negative two sides simultaneously；
Described self-operated measuring unit, by two-sided electrolysis bath grip seal sample, adopt double; two cell construction, sample clamping is enclosed between double; two electrolysis bath, the positive and negative two sides achieving sample automatically measures, there is sample self-closed, liquid feeding, measurement and data processing function, adopt automatization, digitizing technique and measuring technology, improve the precision that tin plate sheet surface chromium electrolysis is measured.
2. the tin plate sheet surface chromium amount electrolysis self-operated measuring unit described in claim 1, it is characterized in that described computer is PC, the setting of startup and two-way constant current supply running parameter for controlling digitial controller, in automatic measurement process, the characteristic value of the electrolysis reaction in described computer real-time acquisition measurement process；After measurement process terminates, described computer is automatically into data processor, obtain the corresponding potential value u of t on electrolytic curve, obtain the electrolysis time Δ T of tin plate sheet surface chromium according to surface chromium electrolysis endpoint method, obtain the surface chromium amount of tin plate according to the calibration factor K of surface chromium electrolysis.
3. the tin plate sheet surface chromium amount electrolysis self-operated measuring unit described in claim 1, it is characterized in that described digitial controller is time schedule controller, in automatic measurement process, sample is closed by described digitial controller sequential control sample closing means chronologically, liquid feeding system adds electrolyte in two-sided electrolysis bath, controlling liquid feeding system and add the liquid feeding time of electrolyte in two-sided electrolysis bath, after measurement process terminates, described digitial controller controls sample closing means and resets.
4. the tin plate sheet surface chromium amount electrolysis self-operated measuring unit described in claim 1, it is characterized in that the opening at described first, second monomer electrolysis bath, it is respectively arranged with first, second sealing ring, when the push rod of sample closing means moves forward and puts in place, second sealing ring of described second comonomer electrolysis bath opening and the first sealing ring close contact of the first monomer electrolysis bath opening, by sample clamping between first, second sealing ring of first, second monomer electrolysis bath opening, reach the purpose that sample seals.
5. the tin plate sheet surface chromium amount electrolysis self-operated measuring unit described in claim 1, it is characterized in that described liquid feeding system includes fluid filling pump, liquid-feeding tube, overflow pipe, seal cup and reagent barrel, fluid filling pump adds electrolyte by liquid-feeding tube to two-sided electrolysis bath, unnecessary electrolyte is spilled over to seal cup from overflow pipe, and it is back in reagent barrel, to guarantee in the inner chamber that electrolyte is completely filled with two-sided electrolysis bath；After tin plate sheet surface chromium electrolysis terminates, two-sided electrolysis bath is opened, and the electrolyte in two-sided electrolysis bath inner chamber is back in reagent barrel by seal cup；The liquid feeding time of its described electrolyte was controlled by the operation time of fluid filling pump, and the operation time of described fluid filling pump is controlled by digitial controller, and user can be set at computer.
6. a measuring method for tin plate sheet surface chromium amount electrolysis self-operated measuring unit as claimed in claim 1, is characterized in that tin plate sheet surface chromium amount is carried out automatically measuring by described self-operated measuring unit according to the following step:
Sample is put in two-sided electrolysis bath, computer sends instruction to digitial controller, the push rod of sample closing means moves forward, two-sided electrolysis bath closes, sample is closed, liquid feeding system adds electrolyte in two-sided electrolysis bath, now two-way digital constant-current source is started working, the electric current i of computer acquisition electrolysis reaction, the characteristic values such as current potential u and time t, when electrolysis stripping to current potential u does not occur significantly to change, measurement is automatically stopped, sample closing means resets, two-sided electrolysis bath is opened, electrolyte discharges to reagent barrel, take out sample, computer is automatically into data processor, mobile mouse obtains the corresponding potential value u of t on electrolytic curve, the electrolysis time Δ T of tin plate sheet surface chromium is obtained according to surface chromium electrolysis endpoint rule, calibration factor K according to surface chromium electrolysis obtains the surface chromium amount of tin plate.
7. a surface chromium electrolysis endpoint method for tin plate sheet surface chromium amount electrolysis self-operated measuring unit as claimed in claim 1, including the acquisition of electrolytic curve, is characterized in that:
Tin plate sheet surface chromium amount electrolytic curve finds change in voltage starting point A point moment t0；
Finding increment 200mvB point moment t1 and A point to B point required time Δ T1, curve linearly section starting point C point moment t2 and A point is to C point required time Δ T2；
When B point t1 and C puts the absolute value≤threshold value d of t2 two Time of day offsets, its corresponding B point or C point are that surface chromium electrolysis peels off terminal, and its corresponding time Δ T1 or Δ T2 is as the electrolysis stripping time Δ T of surface chromium；
When B point t1 and C puts the absolute value > threshold value d of t2 two Time of day offsets, cut-off line starting point C point t2 is the electrolysis stripping terminal of surface chromium, and its corresponding time Δ T2 is as electrolysis stripping time Δ T；
To measuring the unconspicuous sample of straight line starting point, adopting 200mv increment endpoint determination Δ T1 as surface chromium electrolysis stripping time Δ T, now accurately measuring of tin plate sheet surface chromium needs to adopt chemical method measurement carry out and obtain.
8. the surface chromium electrolysis endpoint method described in claim 7, is characterized in that described A point is to B point required time Δ T1=t1-t0, and unit is the second；Described A point is to C point required time Δ T2=t2-t0, and unit is the second.
9. the surface chromium electrolysis endpoint method described in claim 7, it is characterized in that described electrolysis measures endpoint method and measures allowable error according to tin plate sheet surface chromium amount test chamber, formulate 200mV increment and judge that end-point method t1 and straight line starting point judge time difference threshold value d between end-point method t2.
10. the surface chromium electrolysis endpoint method described in claim 7, is characterized in that its described threshold value d determines according to following relationship:
Threshold value d=│ t2-t1 │=mensuration allowable error D ÷ calibration factor K；
Wherein, t1 is the increment 200mvB point moment, and unit is the second；T2 is the curve linearly section starting point C point moment, and unit is the second；Measure allowable error D and formulated according to technological requirement by detecting department and user；The conversion coefficient of the electrolysis that calibration factor K is tin plate sheet surface chromium electrolysis to be obtained with chemical method correlation curve and chemical method, the i.e. calibration factor of tin plate sheet surface chromium electrolysis and chemical method.
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