CN1067157C - Quick measuring method and measuring apparatus for hydrogen content, in aluminium alloy melt - Google Patents
Quick measuring method and measuring apparatus for hydrogen content, in aluminium alloy melt Download PDFInfo
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- CN1067157C CN1067157C CN 95113756 CN95113756A CN1067157C CN 1067157 C CN1067157 C CN 1067157C CN 95113756 CN95113756 CN 95113756 CN 95113756 A CN95113756 A CN 95113756A CN 1067157 C CN1067157 C CN 1067157C
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Abstract
The present invention discloses a method for measuring the hydrogen content in an aluminum alloy under a common casting process condition by measuring the expansion generated in a solidifying process of a test sample cast by aluminum alloy melt because hydrogen is separated out to form needle holes and measuring instrument thereof. The method is convenient, accurate, practical and quick. Beginning with pouring a melt liquid sample into a casting model, a result can be obtained within 2 minutes. The measuring instrument has the advantages of portability, simple operation, low cost and strong adaptability. The measuring instrument can be widely suitable for the production fields of non-ferrous metal metallurgy and casting industry to measure, control and research the hydrogen content of different aluminum alloy melt in scientific research and teaching experiment and can also be used for quickly detecting the gas content of copper alloy.
Description
The invention relates to a field detection technology for hydrogen content of an aluminum alloy melt. In particular to a method and a measuring instrument for rapidly measuring the hydrogen content of an aluminum alloy melt.
Various known methods and instruments for measuring the hydrogen content of the aluminum alloy melt are described in detail in the book P196-P213 of nonferrous metal purification published by university of university. Three of these main methods are listed below:
(1) a reduced pressure solidification method: and taking a measured aluminum alloy melt sample and pouring a sample solidified under a reduced pressure condition. Qualitatively judging whether the hydrogen content of the melt is qualified or not according to the state and degree of a bulge formed on the upper surface of the sample due to hydrogen precipitation in the solidification process and theexperience of an observer; (2) the first bubble method: according to the principle that the temperature and the pressure are different when the first bubble is emitted from the surface of the melt of the aluminum alloy due to different hydrogen contents in the aluminum alloy, the hydrogen content of the measured aluminum alloy melt is obtained by measuring the two parameters and converting the two parameters by a special formula. The two methods have the defects of low measurement speed, human factors and poor accuracy. (3) Gas telemetry: this method is also called Telegas method. The method assumes that the hydrogen in the aluminium alloy melt is uniformly distributed, and inert gas bubbles are introduced into the melt to provide a free surface on which the hydrogen in the melt is distributed Is precipitated in the form of the partial pressure PH of hydrogen in the bubbles over a certain period of time2And the hydrogen content in the melt is balanced. Determination of pH by means of a thermally conductive gassing meter2And simultaneously, measuring the temperature of the melt by using a thermocouple, and converting by using a special formula to obtain the hydrogen content of the measured melt. The method has the disadvantages of complicated instruments and equipment, high cost and complex operation. Furthermore, the measurement speed is still slow, for example, at least 5 minutes is generally required from the start of measurement to the end of measurement.
The invention aims to provide a simple, convenient, quick, accurate and practical method and a measuring instrument for measuring the hydrogen content of an aluminum alloy melt.
The invention has the following theoretical basis and technical scheme: it is generally considered that hydrogen is the only soluble gas in the aluminum alloy melt, and under ordinary atmospheric pressure conditions, the solubility of hydrogen in liquid and solid aluminum alloys is greatly different, and increases with the increase of temperature and decreases with the rise of temperature. Under actual production conditions, the hydrogen content of the aluminum alloy is continuously increased in the process of smelting and heating, on the contrary, the hydrogen content of the aluminum alloy is continuously reduced in the process of solidification, particularly in a temperature range near a solidus line, because the melting degree of the aluminum alloy to hydrogen is suddenly reduced, hydrogen exceeding the critical content of the aluminum alloy is greatly precipitated in an atomic form and forms molecules, and pinholes are relatively intensively formed in the aluminum alloy during solidification, so that the aluminum alloy generates an expansion phenomenon during solidification, and phase diagram analysis shows that various aluminum alloys do not have expansion phase transformation in the solidification stage. Therefore, pinholes formed due to hydrogen evolution are the only cause of the above-mentioned swelling phenomenon, and have been experimentally verified repeatedly.
The pinhole degree of the known aluminum alloy in a room-temperature solid state and the hydrogen content of the aluminum alloy in a liquid state are in a certain corresponding relation, and the higher the hydrogen content is, the more pinholes are, the more serious the pinholes are, and the density is also smaller.
In summary, under certain process conditions, an accurate micro-displacement measurement technology is adopted, the expansion amount and the corresponding electric signal generated in the solidification process of the aluminum alloy melt liquid sample are accurately measured, and the corresponding hydrogen content is obtained through signal processing and data processing.
The invention provides a method for rapidly measuring the hydrogen content of an aluminum alloy melt, which comprises the following steps of taking a liquid sample of the aluminum alloy melt to be measured, pouring the liquid sample into a prefabricated casting mold to form a bar-shaped sample, measuring the axial linear expansion of the sample in the solidification process, and finally obtaining the hydrogen content of the melt to be measured through conversion treatment:
(1) prefabricating a casting mold according to the process requirement of a common sand mold;
(2) mounting a prefabricated casting mold on a machine base, placing a filter screen sheet made of fibers capable of bearing the pouring temperature of an aluminum alloy melt on a sprue of the casting mold, and then mounting a sprue cup;
(3) one end of a measuring rod made of high-purity quartz glass is fixedly connected with a core rod of the displacement sensor through a locking nut, the other end of the measuring rod is inserted into a casting mold measuring process hole, and the insertion depth is limited by a clamping ring arranged on the measuring rod;
(4) the displacement sensor, the measuring rod and the measuring process hole are ensured to be coaxially installed, before measurement, the displacement sensor is adjusted to a measuring zero point through an adjusting knob of a zero adjusting mechanism, namely, the display indicates zero;
(5) a measured aluminum alloy melt liquid sample is poured into a casting mold from a pouring cup to form a bar-shaped sample, the sample expands due to the fact that a pinhole is formed by hydrogen precipitation in the solidification process and mainly shows the expansion of the axial dimension of the sample, the expansion amount is converted into an electric signal through a measuring rod by a displacement sensor, and the hydrogen content of the measuredmelt is displayed by a display after the electric signal is processed by a conversion processor.
The measuring instrument for realizing the method comprises the following steps:
(1) one end of the machine base is provided with a fixed support, the other end of the machine base is provided with a dovetail groove matched with the bottom plate, and the middle part of the machine base is provided with a positioning block for mounting a casting mold;
(2) a bar-shaped sample cavity is arranged in the casting mould, a sprue is reserved on the casting mould, a filter screen sheet is arranged on the sprue, a sprue cup is pressed on the sprue, a mould-discharging process hole is reserved at one end of the casting mould, a measuring process hole is arranged at the other end of the casting mould, after the mould-discharging process hole is tightly plugged by a plug made of refractory materials, the casting mould is arranged on a positioning block, and the plug is tightly leaned against a fixed support;
(3) the box body is fixed on a bottom plate, and the bottom plate is arranged in a dovetail groove on the base and is in sliding fit with the dovetail groove; in the box body, a displacement sensor and a zero setting mechanism thereof are both arranged on a support, the support is fixed on a bottom plate, the displacement sensor is in movable fit with the support and is fixedly connected with the zero setting mechanism, an adjusting knob of the zero setting mechanism is arranged outside the box body, a core rod of the displacement sensor penetrates out of the box body, and the displacement sensor and the zero setting mechanism are in movable fit; outside the box body, the core rod is fixedly connected with the measuring rod through a locking nut, the measuring rod is inserted into the measuring process hole, and the insertion depth is limited by a clamping ring on the measuring rod;
(4) the measured aluminum alloy melt is poured into the casting mold, one end of a formed bar-shaped sample is propped by the plug, the other end of the formed bar-shaped sample is contacted with the measuring rod, when the sample expands, the linear expansion of the axial dimension is transferred to the displacement sensor through the measuring rod, the displacement sensor is converted into an electric signal and is transmitted to the conversion processor, and finally the electric signal is transmitted to the display to display the result, and the conversion processor and the display are arranged on the box body.
Compared with the prior art, the method has the advantages of high measurement speed, accurate and reliable result, no more than 2 minutes from pouring liquid sample to displaying result, and good correspondence between the measured hydrogen content result and the actual pinhole degree or density inspection result. In addition, the instrument has low cost, light structure and simple operation, and is suitable for field use.
The attached drawing is a structural schematic diagram of the rapid hydrogen content measuring instrument for the aluminum alloy melt. In the figure, 1 is a fixed support, 2 is a plug, 3 is a machine base, 4 is a casting mold, 5 is a positioning block, 6 is a measuring rod, 7 is a clamping ring, 8 is a locking nut, 9 is a bottom plate, 10 is a support, 11 is a displacement sensor, 12 is a zero setting mechanism, 13 is a conversion processor, 14 is a display, 15 is a box body, 16 is a sand box, 17 is a filter screen sheet, and 18 is a pouring cup.
The specific embodiments of the invention are described below with reference to the accompanying drawings:
the fixed support (1) is fixedly arranged at the left end of the base (3);
the casting mold (4) is prefabricated, and the raw sand is required to be 1N 100-200, and the wet-pressing strength is required to be 3.5-4N/CM2The wet permeability is 85-95, the moisture is 3.8-4.2%, and the size of the cavity is phi 20 x 200 mm;a sprue is reserved on the upper molded surface of the casting mold (4), and a sprue cup (18) is pressed after a filter screen sheet (17) for aluminum alloy is placed on the sprue; one end of the casting mould (4) is provided with a mould-stripping process hole, and the other end is provided with a measurement process hole. After demolding, demolding for fabrication holesAfter the plugs (2) are plugged tightly, the casting mold (4) is arranged on four positioning blocks (5) on the base (3), and the plugs (2) are required to be close to the fixed support (1);
the box body (15) is fixedly arranged on the bottom plate (9), the bottom plate (9) is assembled in a dovetail groove at the right end of the base (3), and the bottom plate and the base are in sliding fit;
in the box body (15), a bracket (10) is fixed on the bottom plate (9), and a displacement sensor (11) and a zero setting mechanism (12) are both arranged on the bracket (10); the displacement sensor (11) is movably matched with the bracket (10) and is statically matched with the zero setting mechanism (12), an adjusting knob of the displacement sensor is arranged outside the box body (15), a core rod of the displacement sensor (11) penetrates through the box body (15) and is movably matched with the core rod; outside the box body (15), the core rod is fixedly connected with the measuring rod (6) through a locking nut (8), one end of the measuring rod (6) is inserted into a phi 6 multiplied by 35mm measuring process hole of the casting mould (4), the measuring process hole is in a movable fit relation, the insertion depth is 35mm, and the measuring process hole is limited by a clamping ring (7) on the measuring rod (6);
the displacement sensor (11), the measuring process hole of the casting mold (4) and the measuring rod (6) should be coaxial; before pouring, adjusting a knob outside the box body (15) to enable the displacement sensor (11) to be at a measurement zero point, namely indicating that the display (14) is zero;
about 300g of measured aluminum alloy melt is taken and poured into a casting mold (4) from a pouring cup (18) to form a bar-shaped sample with phi 20 multiplied by 200mm, the sample is expanded due to the generation of a pinhole caused by the precipitation of hydrogen in the solidification process, the axial linear expansion of the sample can only be carried out in one direction due to the limitation of a plug (2), the sample is transmitted to a displacement sensor (11) through a measuring rod (6) contacted with the displacement sensor, the expansion amount of the displacement sensor is converted into an electric signal to be output to a conversion processor (13) for signal processing and data processing, and finally, a display (14) displays the measurement result.
The measurement result displayed by the instrument is the hydrogen content grade value corresponding to the pinhole degree of the casting or the ingot cast by the measured melt, so the method is more visual, accurate and reliable, when the measurement display value is less than or equal to the pinhole degree grade of the technical requirement, the measured aluminum alloy melt is re-refined, the liquid sample is taken, the measurement is repeated until the display result meets the technical requirement, and the casting or the ingot is cast.
The measuring method and the measuring instrument provided by the invention are suitable for measuring the hydrogen content of various aluminum alloy melts and researching and controlling pinholes in production sites, scientific research and teaching experiments. And the method can also be suitable for measuring and controlling the gas content of various copper alloys.
Claims (2)
1. A method for quickly measuring hydrogen content in molten aluminium alloy includes such steps as pouring the liquid sample of molten aluminium alloy to be measured into prefabricated mould to form a bar-shaped specimen, measuring the axial linear expansion of said specimen during solidification, and converting to obtain the hydrogen content of molten aluminium alloy by the following steps:
(1) prefabricating a casting mold according to the process requirement of a common sand mold;
(2) mounting a prefabricated casting mold on a machine base, placing a filter screen sheet made of fibers capable of bearing the pouring temperature of an aluminum alloy melt on a sprue of the casting mold, and then mounting a sprue cup;
(3) one end of a measuring rod made of high-purity quartz glass is fixedly connected with a core rod of the displacement sensor through a locking nut, the other end of the measuring rod is inserted into a casting mold measuring process hole, and the insertion depth is limited by a clamping ring arranged on the measuring rod;
(4) the displacement sensor, the measuring rod and the measuring process hole are ensured to be coaxially installed, before measurement, the displacement sensor is adjusted to a measuring zero point through an adjusting knob of a zero adjusting mechanism, namely, the display indicates zero;
(5) a measured aluminum alloy melt liquid sample is poured into a casting mold from a pouring cup to form a bar-shaped sample, the sample expands due to the fact that a pinhole is formed by hydrogen precipitation in the solidification process and mainly shows the expansion of the axial dimension of the sample, the expansion amount is converted into an electric signal through a measuring rod by a displacement sensor, and the hydrogen content of the measured melt is displayed by a display after the electric signal is processed by a conversion processor.
2. A test instrument specifically designed for use with the method of claim 1, comprising:
(1) one end of the machine base is provided with a fixed support, the other end of the machine base is provided with a dovetail groove matched with the bottom plate, and the middle part of the machine base is provided with a positioning block for mounting a casting mold;
(2) a bar-shaped sample cavity is arranged in the casting mould, a sprue is reserved on the casting mould, a filter screen sheet is arranged on the sprue, a sprue cup is pressed on the sprue, a mould-discharging process hole is reserved at one end of the casting mould, a measuring process hole is arranged at the other end of the casting mould, after the mould-discharging process hole is tightly plugged by a plug made of refractory materials, the casting mould is arranged on a positioning block, and the plug is tightly leaned against a fixed support;
(3) the box body is fixed on a bottom plate, and the bottom plate is arranged in a dovetail groove on the base and is in sliding fit with the dovetail groove; in the box body, a displacement sensor and a zero setting mechanism thereof are both arranged on a support, the support is fixed on a bottom plate, the displacement sensor is in movable fit with the support and is fixedly connected with the zero setting mechanism, an adjusting knob of the zero setting mechanism is arranged outside the box body, a core rod of the displacement sensor penetrates out of the box body, and the displacement sensor and the zero setting mechanism are in movable fit; outside the box body, the core rod is fixedly connected with the measuring rod through a locking nut, the measuring rod is inserted into the measuring process hole, and the insertion depth is limited by a clamping ring on the measuring rod;
(4) the measured aluminum alloy melt is poured into the casting mold, one end of a formed bar-shaped sample is propped by the plug, the other end of the formed bar-shaped sample is contacted with the measuring rod, when the sample expands, the linear expansion of the axial dimension is transferred to the displacement sensor through the measuring rod, the displacement sensor is converted into an electric signal and is transmitted to the conversion processor, finally the electric signal is transmitted to the display to display the result, and the conversion processor and the display are arranged on the box body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95113756 CN1067157C (en) | 1995-01-26 | 1995-10-13 | Quick measuring method and measuring apparatus for hydrogen content, in aluminium alloy melt |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95100047 | 1995-01-26 | ||
| CN95100047.0 | 1995-01-26 | ||
| CN 95113756 CN1067157C (en) | 1995-01-26 | 1995-10-13 | Quick measuring method and measuring apparatus for hydrogen content, in aluminium alloy melt |
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| Publication Number | Publication Date |
|---|---|
| CN1157922A CN1157922A (en) | 1997-08-27 |
| CN1067157C true CN1067157C (en) | 2001-06-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 95113756 Expired - Fee Related CN1067157C (en) | 1995-01-26 | 1995-10-13 | Quick measuring method and measuring apparatus for hydrogen content, in aluminium alloy melt |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101813595B (en) * | 2009-07-13 | 2011-11-23 | 哈尔滨理工大学 | Device of quickly measuring hydrogen content in aluminium alloy fusant |
| CN104792657A (en) * | 2015-04-03 | 2015-07-22 | 江苏新安驰铝业有限公司 | Method for detecting influence degree of hydrogen content of molten aluminum |
| CN106501301A (en) * | 2015-09-07 | 2017-03-15 | 哈尔滨理工大学 | Magnesium iron stokehold heat analysis-eutectic expansion device for fast detecting and detection method |
| CN109536755B (en) * | 2018-12-13 | 2020-11-27 | 中国兵器工业第五九研究所 | Intelligent control system for air content of aluminum alloy melt |
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