JPS5911861B2 - Inspection method for glass joints - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for inspecting joints of glass joints.

A so-called dip sealing method in which the parts to be joined of a pair of members to be joined are mutually polymerized, and the polymerized parts to be joined are immersed in molten glass that is being heated with electricity and pulled up to glass-bond the members to be joined, A soft metal thin plate coated with glass on both the front and back surfaces is interposed between the surfaces to be joined of a pair of members to be joined, polymerized, and heated while being pressed together to melt the coated glass and bond the members to each other with glass. The development of glass bonding materials for bonding has made it easier to bond glass, ceramics, metals, and other similar materials, as well as dissimilar materials. It has become possible to join glass even with materials that were considered difficult to join with solder, and the range of applications has expanded.

However, in order to detect the quality of the bond in the glass bonded body obtained in this way, conventional methods have been to apply a load to the bonded part and measure the shear stress(V), or to cut the bonded part and examine the cut surface using a microscope. This method was used to determine whether there were air bubbles or chips in the glass. However, all of these conventional inspection methods are destructive tests, and 100% inspection is not possible. Therefore, not only are defective products easily mixed into the product, but also the deviation of test data is large in load-destructive tests, and a large number of samples are required. V) It has the disadvantage of requiring a lot of effort and use. In addition, another important item for detecting the quality of bonding of a bonded body is a repeated thermal shock test in which the bonded body is repeatedly immersed in hot water and cold water alternately and inspected for the presence or absence of abnormalities.

However, this test is also susceptible to the heat capacity of the bonded body and the quality of heat conduction, and has disadvantages such as large deviations in data and the tendency for the bonded body to rust.Furthermore, this test is also a type of destructive test. Therefore, as mentioned above, there were drawbacks such as the impossibility of 100% inspection. The purpose of the present invention is to eliminate the drawbacks of the prior art and provide a method for inspecting a glass bonded body, which enables 100% inspection and reliably determines the quality of the glass bonded body. Applying a voltage between the joined members of the joined body formed by glass joining the members,
The purpose of this is to judge the bonding condition of the glass joint and/or its strength from the relationship between this voltage and the current flowing through the glass joint.

15, details of the present invention will be explained with reference to the illustrated embodiments.

Reference numerals 1 and 2 denote a pair of conductive members to be joined, such as a pair of metal tubes, whose end surfaces face each other with a minute gap in between; 3 a glass layer interposed between these metal tubes 1 and 2 to glass-bond them; The vicinity of the end face including this glass layer 3 is referred to as a joint portion 4.

5 is a step-down transformer whose output side ends are connected to the pair of members 1 and 2 to be joined, 6 is a step-down autotransformer whose output side is connected to the input side of this step-down transformer 5, and 7 is this autotransformer 6. 9 is an ammeter inserted between the step-down transformer 5 and one of the members 2 to be joined; 10 is the switch inserted between the step-down transformer 5 and the AC power source 8;
This is a voltmeter connected across the output side of the .

Now, the autotransformer 6 is adjusted, the switch 7 is closed, and a voltage v is applied between the two members 1 and 2 to be welded.

Then, a current I flows through the junction 4 due to the voltage V. This voltage V} and current 1 are measured by the aforementioned voltmeter 10 and ammeter 9. This current 1 depends not only on the voltage V and the area of the glass layer 3, but also on the thickness of the glass layer 3, this layer 3
It is determined by the air bubbles contained therein, the presence or absence of chips in this layer 3, etc. The thickness of the glass layer 3 needs to be as thin as possible in order to obtain good glass bonding, and is several tens of microns thick.
It is said that a thickness of 1 or less is better, and a thickness of this order exhibits a small electrical resistance of 0.1a4 to 0.1a4 or less, making it easier to conduct electricity. As the thickness of the glass layer 3 of the joint part 4 becomes thinner, the electrical resistance decreases. When chipping occurs, the electrical resistance increases and the bonding strength decreases. Therefore, in a given glass bonded body, there is a range of electrical resistance values for good bonding, and this is determined experimentally in advance, and the voltage v and current 1 are calculated as described above. By measuring the relationship and knowing whether it is within an appropriate range, the bonding strength can be determined to a certain extent. Further, as the voltage V is increased, the voltage changes as shown in the graph shown in the second figure.

In this graph, the horizontal axis shows voltage in units of V, and the vertical axis shows current! ! : Measured in units of A. Then, normally, as shown by curve A, current 1 also changes according to voltage V. However, if there are bubbles in the glass layer 3 or if the thickness is not uniform, irregular changes will occur as shown in curve B. The presence or absence of defects can be determined. On the other hand, if current is passed through the glass joint 4, the joint 4 will be heated by Joule heat, so adjust the autotransformer 6 in advance so that the amount of heat generated is appropriate, and close the switch 7. If current is applied to the bonded portion 4, a thermal shock test can be performed on the bonded portion 4.

According to this method, since the thermal shock of the joint part 4 is appropriately performed, the deviation of the measured values is smaller than that of the conventional method of heating from the outside, and the reproducibility of the measured values can be improved.
Those damaged in this thermal shock test have a rapid increase in electrical resistance, which can be easily determined from the movement of the ammeter 9, and can be reliably removed, making it possible to conduct a complete inspection. Next, a specific example will be described.

Parts to be joined 1, 2...Soft steel pipe glass layer 3...PbO with an outer diameter of 131t1L and an inner diameter of 9T1LTIL
-B2O3-SiO2 glass thermal expansion coefficient 112×10-
7/C. Softening temperature: 354°C First, the end faces of the members to be joined 1 and 2 to be joined are
It is immersed in a glass liquid melted to a viscosity of 100 poise or less during electrical heating and then pulled up to coat it with glass.

Thereafter, the end surfaces of the members to be joined 1 and 2 to be joined are heated while being pressed together to glass-join them. In this manner, 50 glass bonded bodies were made 9 and assembled as shown in Figure 1, and the following tests were conducted. First, the desired shear stress is 200 kg.
It was previously confirmed through experiments that a current range of 15 to 30 A at an applied voltage of 1 V is appropriate for testing whether the voltage is 4i or more. Next, when a voltage of 1V was passed through the test article and the current was measured, the following results were obtained.

48 items passed the test with a current of 15 to 20A.
Those that failed with less than 5A
Next, a thermal shock was applied to the two pieces by applying a current at a voltage of 40 W for 30 seconds, and the presence or absence of damage at the joint was examined, and the following results were obtained.

48 items that passed the current test Items that passed the Nakamoto test 44 items that passed the current test 48 Items that were damaged during the Nakamoto test
The two that failed the four-piece current test were all damaged.

When the shear fracture stress was determined for the 44 pieces that passed this thermal shock test, they all ranged from 970 to 280 kg/
It was confirmed that the value within the range of Flow 2 and above the desired value of Vl2OOkT2 is considered to be a good product. However, the parts to be joined to which this test is applied are not limited to the same type, and may be combinations of stainless steel and copper, stainless steel and aluminum, etc., or composites of alumina and titanium carbide, etc., as long as they are electrically conductive. But that's fine.

In addition, in the case of a combination of parts to be joined that have large differences in coefficient of thermal expansion, such as a combination of stainless steel and mild steel that cannot be joined directly with glass solder, a thin plate of soft metal such as copper or aluminum may be used between the joining surfaces. Good bonding can be achieved by glass bonding using a method of glass bonding, and since a glass layer is interposed between both bonding surfaces and the soft metal thin plate, the test method of the present invention can also be applied to this case. Also, if the thickness of the glass layer is not uniform,
The current flows in a concentrated manner in the thin part of the glass layer, causing localized differences in heat generation, so inspection is easier if a thermometer is used in combination.

Further, the current used in the test method of the present invention is not limited to alternating current, but may be direct current or high frequency.

As described above, the present invention applies a voltage between the members to be joined in a joined body formed by glass-bonding a pair of conductive members to be joined, and causes current to flow through the glass joint by this voltage. The glass bonded structure has a good relationship with the current.
A method for inspecting a glass bonded body that enables 100% inspection and reliably determines the quality of the glass bonded body, since the bonding condition of the glass bonded portion and/or its strength is determined by comparing the relationship between the voltage and current that are applied. can be provided.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of an embodiment of the glass bonded body inspection method of the present invention, and Fig. 2 similarly shows the relationship between the applied voltage and the current flowing through the glass bonded part due to this voltage. It is a graph. 1, 2... Member to be joined, 3... Glass layer, 4... Joining portion.

Claims (1)

[Claims] 1. A voltage is applied between the members to be joined in a bonded body formed by glass-bonding a pair of conductive members to be joined, and the relationship between this voltage and the current flowing through the glass bonded portion due to this voltage is determined. A method for inspecting a glass bonded body, the method comprising: determining the quality of the bonding state and/or strength of the glass bonded portion by comparing the relationship between voltage and current in a bonded body that has been successfully glass bonded.