CN103105395A - Determination method of furfuryl alcohol content in no-bake furan resin for casting - Google Patents

Abstract

The invention relates to a determination method of furfuryl alcohol content in no-bake furan resin for casting, and belongs to the technical field of detection. The determination method of furfuryl alcohol content in no-bake furan resin for casting comprises the following steps of: determining the content of main ingredient furfuryl alcohol in furan resin by adopting back titration of iodometry, wherein the reaction flow mainly comprises the following substeps of: firstly carrying out bromination reaction on samples, bromine, glacial acetic acid and hydrochloric acid; then dropping in potassium iodide for replacement reaction after bromination; and finally dropping in insodium thiosulfate for reaction. Through the determination method provided by the invention, the furfuryl alcohol content in no-bake furan resin for casting can be determined, so that on one hand, the furfuryl alcohol content can be grasped effectively when the no-bake furan resin is in check-out, the quality for using no-bake furan resin is ensured, the cast quality is stabilized, and the cast rejection rate caused by casts is lowered greatly, and on the other hand, the quality of resin can be evaluated through sample test when new suppliers are developed, so that the test cycle is shortened, the hazard and loss of material object test failure are lowered, and meanwhile basis is provided for confirming the price of resin.

Description

The casting assay method of furfuryl alcohol content in self-hardening furan resin

Technical field

The present invention relates to a kind of assay method of casting with furfuryl alcohol content in self-hardening furan resin, belong to the detection technique field.

Background technology

In modern Foundry Production technology, the characteristics such as self-hardening furan resin sand is due to good stability of the dimension, and mould strength is high, and collapsibility is good are widely used in producing various complex-shaped, foundry goods that dimension precision requirement is high.

The enterprise product of domestic production wind power casting mainly comprises all kinds of wind power castings such as wheel hub, base (cabin seat), bearing seat, gear housing, planet carrier, because the technical requirement of wind power casting is higher, must reach the ultrasonic flaw detection requirement as foundry goods compactness, the foundry goods degree of purity reaches magnetic nondestructive examination requirement, therefore generally selects the casting self-hardening furan resin sand as Modeling Material.

Directly have influence on the elevated temperature strength of casting mold due to the height of furfuryl alcohol content in furane resin, therefore longer due to cast, setting time for the casting of heavy castings, in order to guarantee foundry goods compactness and presentation quality, must select the higher high furfuryl alcohol content self-hardening furan resin of elevated temperature strength, the furfuryl alcohol content in effective detection and grasp furane resin is to guaranteeing that casting quality just seems most important thus.

Existing national standard " casting use self-hardening furan resin " (JB/T7526-2008) has been stipulated the assay method of viscosity, density, free formaldehyde, nitrogen content, free phenol, room temperature tensile strength, does not stipulate but how the direct furfuryl alcohol content that affects elevated temperature strength is measured.

Summary of the invention

The objective of the invention is to overcome above-mentioned weak point, a kind of assay method of casting with furfuryl alcohol content in self-hardening furan resin is provided, measure the content of Main Ingredients and Appearance furfuryl alcohol in furane resin by the back titration of iodimetric titration.

According to technical scheme provided by the invention, measure the content of Main Ingredients and Appearance furfuryl alcohol in furane resin by the back titration of iodimetric titration.

At first its reaction process is mainly and carries out bromination reaction by sample and bromine, glacial acetic acid, hydrochloric acid, splashes into potassium iodide after bromination again and carries out displacement reaction, splashes at last the sodium thiosulfate reaction.

Its main chemical reactions equation is as follows:

Br ₂+2KI=2KBr+I ₂

2Na ₂S ₂O ₃+I ₂=Na ₂S ₄O ₆+2NaI。

A kind of assay method of casting with furfuryl alcohol content in self-hardening furan resin, step is as follows:

(1) demarcation of 0.1mol/L sodium thiosulfate, concentration demarcated in record is C:

A, accurately take 26g sodium thiosulfate Na ₂S ₂O ₃5H ₂O or 16g Sodium Thio Sulphate(Anhydrous), then add the 0.2g natrium carbonicum calcinatum, be dissolved in 1000mL water, slowly boil 10 minutes, cooling, lucifuge is filtered after two weeks and is used;

B, take 0.18g and be placed in iodine flask in 120 ℃ ± 2 ℃ base weight potassium chromates that are dried to constant weight, weight is accurate to 0.1000g, is dissolved in 25mL water, and adding 2g potassium iodide and 20mL mass concentration is 20% sulfuric acid solution, shakes up, and places 10min in the dark place;

C, add 150mL water, sodium thiosulfate solution titrated to the b solution for preparing with step a becomes bright green by blueness, carries out simultaneously blank test, is calculated as follows demarcation concentration:

$C\left({\mathrm{Na}}_2{S}_2{O}_3\right)=\frac{m\×1000}{(V_1-V_2)\×M}$

In formula: m is the accurate numerical value of the quality of potassium dichromate, and unit is g; V ₁Be the numerical value of the volume of sodium thiosulfate, unit is mL; V ₂Be the numerical value of the volume of blank test hypo solution, unit is mL; M is the numerical value of the molal weight of potassium dichromate, and unit is g/mol;

(2) blank assay: in the ground triangular flask of 200mL sky, adding the bromine solutions of 10mL glacial acetic acid, 25mL and 10mL mass concentration with transfer pipet successively is 20% HCl solution, and vibration, make solution be dark brown immediately; Sample is placed in dark cold place 10min; Taking-up is placed in the sample of dark cold place, and adding the 10mL mass concentration is 10% liquor kalii iodide, immediately vibration;

(3) measure: get sample 0.400g to be detected and be placed in 200mL ground triangular flask, recording sample weight is G, adds the 10mL glacial acetic acid with transfer pipet; The bromine solutions that adds 25mL, 10mL mass concentration are 20% HCl solution, and vibration, make solution be dark brown immediately; Sample is placed in dark cold place 10min; Taking-up is placed in the sample of dark cold place, and adding the 10mL mass concentration is 10% liquor kalii iodide, immediately vibration;

(4) titration: the 0.1mol/L sodium thiosulfate of demarcating with step (1) is titrated to sample and is faint yellow; Be that 1% starch solution drops to sample to colourless with mass concentration; Continue to add starch solution, the vibration triangular flask is read the mL number of the sodium thiosulfate that consumes to no longer variable color of sample, and space record is V, and sample is recorded as V ₁

(5) calculating of analysis result: according to the reading substitution following formula of above-mentioned steps record,

In formula: V is sodium thiosulfate blank titration number, and unit is mL; V ₁Be sodium thiosulfate sample titration number, unit is mL; 2.45 be the mg number of furfuryl alcohol in every duplicate samples; C is that sodium thiosulfate is demarcated content, and unit is mol/L; G is sample size, and unit is g.

Take potassium bromide 2g, potassium bromate 1.4g, after measuring the abundant mixing of 500mL water with graduated cylinder and get final product.

The present invention has following advantage: can determine by assay method of the present invention the furfuryl alcohol content of casting with in self-hardening furan resin, thereby can effectively hold furfuryl alcohol content on the one hand when the self-hardening furan resin ware-house-in inspection, guarantee to use the quality of self-hardening furan resin, stablize the casting mold quality, the casting wasted product rate that causes due to the casting mold reason is declined to a great extent; Just can pass judgment on by specimen test the quality of resin on the other hand in the time of the new supplier of exploitation, thereby shorten the test period, reduce risk and the loss of actual loading test failure, simultaneously for determining that resin price provides foundation.

Embodiment

Embodiment 1

(1) demarcation of 0.1mol/L sodium thiosulfate, concentration demarcated in record is C:

Accurately take 26g sodium thiosulfate (Na ₂S ₂O ₃5H ₂O) (or 16g Sodium Thio Sulphate(Anhydrous)), add the 0.2g natrium carbonicum calcinatum, is dissolved in 1000ml water, slowly boils 10 minutes, and be cooling, and lucifuge is filtered after two weeks and used.

Take 0.18g(and be accurate to 0.1000g) be placed in iodine flask in 120 ℃ ± 2 ℃ base weight potassium chromates that are dried to constant weight, be dissolved in 25ml water, add the sulfuric acid solution of 2g potassium iodide and 20ml (20%), shake up, place 10min in the dark place.

Add 150ml water, become bright green with sodium thiosulfate solution titrated to the solution for preparing by blueness, carry out simultaneously blank test.

$C\left({\mathrm{Na}}_2{S}_2{O}_3\right)=\frac{m\×1000}{(V_1-V_2)\×M}$

In formula: m---the accurate numerical value of the quality of potassium dichromate, unit are gram (g)

V ₁---the numerical value of the volume of sodium thiosulfate, unit are milliliter (ml)

V ₂The numerical value of the volume of------blank test hypo solution, unit are milliliter (ml)

The numerical value of the molal weight of M---potassium dichromate, unit are gram/every mole (g/mol)

The configuration of 10%KI solution: add the 50g potassium iodide in the graduated cylinder of 500mL, add distilled water diluting to scale, stir;

The configuration of 20%HCL solution: add the water of 220mL in the graduated cylinder of 500mL, more slowly add HCl(35%) to the 500mL scale mark, stir with glass bar.

The configuration of 1% starch solution: put into 1g starch in the 10mL beaker, 5mL distilled water is heated to pasty state standby after dissolving; Add 95mL distilled water to be heated to 60-70 ℃ in the 200mL beaker, pour pasty state starch into and be stirred to dissolving

The configuration of bromine solutions: take potassium bromide 2g, potassium bromate 1.4g pours in 500ml cranberry glass bottle; Measure 500mL water with graduated cylinder, pour in bottle, fully mixing.

Relate to instrument and equipment: ten thousand/analytical balance; Buret; 200ml ground triangular flask; 10ml, 200ml beaker; The 500ml graduated cylinder; 10ml, 25ml transfer pipet.

(2) blank assay: in the ground triangular flask of 200mL sky, add the 10mL glacial acetic acid with transfer pipet, add the 10mL glacial acetic acid with transfer pipet; The bromine solutions that adds 25mL, 10mL mass concentration are 20% HCl solution, and vibration, make solution be dark brown immediately; Sample is placed in dark cold place 10min; Taking-up is placed in the sample of dark cold place, and adding the 10mL mass concentration is 10% liquor kalii iodide, immediately vibration.

(3) measure: sample is taken the 0.0400g sample be placed in 200ml ground triangular flask, add the 10ml glacial acetic acid with transfer pipet; Add the 25ml bromine solutions, 10ml HCl (20%), vibration, make solution be dark brown immediately; Sample is placed in dark cold place 10min, takes out sample, add 10ml liquor kalii iodide (10%), immediately vibration;

(4) titration: be titrated to sample with 0.1N sodium thiosulfate and be faint yellow; Add starch solution (1%), sample is titrated to colourless; Add several starch solutions, the vibration triangular flask is to no longer variable color of sample again; Read the ml number of the sodium thiosulfate that consumes

(5) calculating of analysis result: according to the reading substitution following formula of above-mentioned steps record,

In formula: V-sodium thiosulfate blank titration number, unit is ml

V ₁-sodium thiosulfate sample titration number, unit is ml

2.45-the mg number of furfuryl alcohol in every duplicate samples

C-sodium thiosulfate is demarcated content, and unit is mol/L

G-sample size, unit are g.

After adopting this method of inspection, we have increased this Interventions Requested in self-hardening furan resin ware-house-in inspection standard, and come into effect check, have effectively guaranteed to use the quality of self-hardening furan resin, stablized the casting mold quality, the casting wasted product rate that causes due to the casting mold reason is declined to a great extent.

After adopting this method of inspection, we just can pass judgment on by specimen test the quality of resin in the time of the new supplier of exploitation, thereby have shortened the test period, have reduced risk and the loss of actual loading test failure, simultaneously for determining that resin price provides foundation.

Application Example 1

The 86-A type furane resin that certain factory produces, to factory's ware-house-in inspection the time, furfuryl alcohol content is detected by the described process of embodiment 1, testing result furfuryl alcohol content is 77.8%, do not reach 80% regulation technical requirement, do simultaneously parallel experiment with the standard model of the furfuryl alcohol content 82% that keeps sample during revision test, the result standard sample size is 82.2%, first article is 77.9%, therefore be judged as defectively, make handling return, effectively avoided issuable quality problems.

Application Example 2

A, B, three sampling of C have been selected simultaneously when the new supplier of exploitation, by sample furfuryl alcohol content is detected by the described process of embodiment 1, and do simultaneously parallel experiment with 82% standard model, testing result A:78.1%, B:73.6%, C:83.4%, standard model: 82.1%, the last C sample that directly filters out technical requirement up to specification carries out small quantities of actual loading test, the various wastes of having avoided blind trial to cause, and qualified C sample is kept sample, be convenient to compare when producing the quality dispute from now on.

Application Example 3

The 86-A type furane resin procurement price that certain factory director's phase supplies is per ton 20000 yuan of left and right, process according to embodiment 1 detects the furfuryl alcohol content value reality that obtains Shang Xia 82%, and the market price of furfuryl alcohol is because the supplydemand relationship fluctuation is larger, may be 15000 yuan of left and right in the time of low, therefore 15000 yuan of the market prices by furfuryl alcohol are calculated, the reasonable price of directly extrapolating furane resin should be 15500 yuan of left and right, in time require supplier to adjust the confession commodity price of furane resin, reduced production cost.

Claims (2)

1. a kind of assay method of furfuryl alcohol content in no-hardening furan resin for casting is characterized in that the steps are as follows: (1) For the calibration of 0.1mol/L sodium thiosulfate, record the calibration concentration as C: a. Accurately weigh 26g of sodium thiosulfate Na ₂ S ₂ O ₃ 5H ₂ O or 16g of anhydrous sodium thiosulfate, then add 0.2g of anhydrous sodium carbonate, dissolve in 1000mL of water, boil slowly for 10 minutes, cool , for filtering after two weeks in dark; b. Weigh 0.18g of benchmark potassium dichromate dried to constant weight at 120°C±2°C, place it in an iodine volumetric flask, the weight is accurate to 0.1000g, dissolve it in 25mL of water, add 2g of potassium iodide and 20mL of mass concentration to be 20% of sulfuric acid solution, shake well, and place in the dark for 10 minutes; c. Add 150mL of water, titrate with the sodium thiosulfate solution prepared in step a until the solution in b turns from blue to bright green, and carry out a blank test at the same time, and calculate the calibration concentration according to the following formula: $\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Na</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 1000</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}$ In the formula: m is the accurate numerical value of the quality of potassium dichromate, unit is g; V ₁ is the numerical value of the volume of sodium thiosulfate, unit is mL; V ₂ is the numerical value of the volume of blank test sodium thiosulfate solution, The unit is mL; M is the numerical value of the molar mass of potassium dichromate, and the unit is g/mol; (2) Blank experiment: Add 10mL of glacial acetic acid, 25mL of bromine solution and 10mL of HCl solution with a mass concentration of 20% to a 200mL empty Erlenmeyer flask with a pipette in turn, shake immediately to make the solution brown; Place the sample in a cool and dark place for 10 minutes; take out the sample placed in a cool and dark place, add 10 mL of potassium iodide solution with a mass concentration of 10%, and shake immediately; (3) Determination: Take 0.400g of the sample to be tested and put it in a 200mL ground-mouth Erlenmeyer flask, record the weight of the sample as G, add 10mL of glacial acetic acid with a pipette; add 25mL of bromine solution, 10mL of 20% mass concentration HCl solution, shake immediately to make the solution brown; place the sample in a cool and dark place for 10 minutes; take out the sample placed in a cool and dark place, add 10 mL of potassium iodide solution with a mass concentration of 10%, and shake immediately; (4) Titration: Titrate with 0.1mol/L sodium thiosulfate calibrated in step (1) until the sample is light yellow; drip the starch solution with a mass concentration of 1% until the sample is colorless; continue to add starch solution, Shake the Erlenmeyer flask until the sample no longer changes color, read out the mL of sodium thiosulfate consumed, record the blank as V, and record the sample as V ₁ ; (5) Calculation of analysis results: Substitute the readings recorded according to the above steps into the following formula,

In formula: V is the sodium thiosulfate blank titration number, unit is mL; V ₁ is the sodium thiosulfate sample titration number, unit is mL; 2.45 is the mg number of furfuryl alcohol in every sample; C is sodium thiosulfate Calibration content, the unit is mol/L; G is the sample amount, the unit is g. 2. the assay method of furfuryl alcohol content in no-hardening furan resin for casting as claimed in claim 1 is characterized in that described bromine solution configuration process is as follows: take by weighing Potassium Bromide 2g, Potassium Bromate 1.4g, measure 500mL water fully with graduated cylinder Serve after mixing.