JPS6322610Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a scanning electron microscope (SEM) configured to cooperate with a material fatigue testing device and observe fatigue damage of a test piece due to its load.
In order to observe fatigue damage on test specimens, especially at high temperatures, a special electric furnace is used to house the specimen support section of the material fatigue testing device and the specimen supported therein, which is installed inside the vacuum chamber of a scanning electron microscope. The present invention relates to a heating device for a scanning electron microscope.

In general, a scanning electron microscope scans a specimen with a focused electron beam obtained through an electron lens, captures and amplifies the secondary electrons emitted from each point on the specimen, and uses a cathode beam for observation. It is configured to modulate the brightness of the tube (CRT) and synchronize the scanning on the test piece with the scanning of the CRT to form a secondary electron image on the screen of the CRT.

Conventionally, it has been widely practiced in the technical field to observe fatigue damage in metal materials using a scanning electron microscope as described above. It was considered to be extremely difficult in some cases. This means that the test piece
When a high temperature is maintained in the vacuum chamber of the SEM, the scanning of the electron beam and The emission of secondary electrons is disturbed and becomes noise,
This is due to the fact that a clear secondary electron image cannot be obtained.

The object of the present invention is to provide a heating device for a scanning electron microscope.

The present invention also provides a heating device for a scanning electron microscope, which is equipped with an electric furnace in the vacuum chamber of the SEM that has a special structure that can heat the specimen without reducing the quality of the secondary electron image. The purpose is to

Furthermore, the present invention provides a heating device for a scanning electron microscope equipped with an electric furnace having electrical characteristics such that the electrical energy supplied for heating the specimen does not affect the quality of the secondary electron image of the SEM. It is intended to.

The invention will be described below with reference to illustrated embodiments.

FIG. 1 shows a specific structure within a vacuum chamber 1 of a scanning electron microscope according to the present invention, which is constructed to be able to cooperate with a loading section of a material fatigue testing apparatus.

The electric furnace 2 has a circular or rectangular cross section, for example, and includes a heater 3, first and second metal shield plates 4 having the functions of an electric shield and a heat radiation shield.
It is formed into a laminated structure consisting of 5. The electric furnace 2 is
It is fixed to the flange 7 via the insulator 6, and further fixed to the fixed flange 8 by a suitable support member (not shown) provided along the longitudinal direction of the electric furnace 2. The electric furnace 2 also has a hole 11 for scanning a focused electron beam obtained through an electron lens 9 over a test piece 10 and capturing secondary electrons emitted from the test piece. In order to prevent the generation of noise, the hole is preferably formed in the shape of a substantially truncated cone having its maximum diameter at the outer wall of the electric furnace 2.

A test piece 10 housed in the electric furnace 2 is supported between the tip of the fixed rod 12 and the tip of the actuating rod 13. The fixing rod 12 is fixed to the flange 7 through the insulator 6, and the actuating rod 13 is fixed to the flange 7.
is guided through a fixed flange 8 into a suitable cylinder (not shown) of a material fatigue testing device so as to be able to reciprocate.

Therefore, with such a configuration, for example, the actuating rod 13 can be moved outward (in the direction of the arrow) to remove the test piece 10.
By applying a tensile load to the test piece 10 and supplying a heating current to the heater 3, it becomes possible to observe fatigue damage of the test piece 10 in a high temperature state through the hole 11.

FIG. 2 shows an electrical circuit diagram related to the electric furnace 2, and as explained below, the circuit includes:
In order to obtain a clear secondary electron image of the SEM, the influence on the electron beam from the electron lens 9 and the secondary electrons emitted from the specimen 10 is removed or minimized.

The heating element 20 of the heater 3 is formed as a non-inductive winding, one end of which is connected to a variable DC current source 21 controlled by a temperature controller, for example, and the other end connected to the reference potential Re of the SEM.・Connected to. Therefore, the magnetic fields generated by the current flowing through each of the adjacent heating elements 20 cancel out, and changes in magnetic flux are minimized by the use of the DC current source 21. Furthermore, both the first and second metal shield plates 4, 5 are connected to the reference potential Re of the SEM in order to provide electrical shielding.

As described in detail above, according to the present invention, a secondary electron image of a test piece in a high temperature state can be observed or photographed using a relatively simple and inexpensive device.
In particular, in actual observation, under normal operating conditions of the SEM, when the inside of the electric furnace 2, that is, the surface of the test piece, is maintained at a high temperature of about 800°C, the hole 11 of the electric furnace 2 dimension from the scanning point on the specimen to hole 1
The ratio α/β of the distance α to an arbitrary point along the inner wall surface of hole 11 and the diameter β of hole 11 at that arbitrary point is approximately
The clearest SEM images are obtained when the value is between 0.7 and 1.3.

The present invention has been described as a scanning electron microscope for observing fatigue damage, which is equipped with an electric furnace that cooperates with a material fatigue testing device. It is also clear that it can be used for observation.

[Brief explanation of drawings]

FIG. 1 shows a specific structure of an embodiment of the present invention which is configured to be able to cooperate with a loading section of a material fatigue testing apparatus. FIG. 2 is an electrical circuit diagram of an embodiment of the present invention. Code explanation, 1: Vacuum chamber, 2: Electric furnace,
3: Heater, 4, 5: Shield plate, 6: Insulator,
7: Flange, 8: Fixed flange, 9: Electronic lens, 10: Test piece, 11: Hole, 12: Fixed rod, 13: Operating rod, 20: Heating element, 21:
DC current source.

Claims (1)

[Scope of utility model registration request] A scanning electron microscope equipped with an electric furnace connected to a loading cylinder of a material fatigue testing device and capable of storing the test piece in a vacuum chamber of the scanning electron microscope in order to observe fatigue damage of the test piece under high temperature conditions. In the heating device for use in a heating device, the electric furnace includes a heater having a heating element formed in a non-inductive winding that substantially surrounds the test piece, at least one metal shield, and scanning an electron beam over the test piece. and a hole for capturing secondary electrons emitted therefrom;
one end of the non-inductive winding is connected to a D, C current source, the other end and the metal shield are connected to a reference potential of the scanning electron microscope, and the hole is connected to an outer wall of the electric furnace. It has an approximately truncated conical shape with a maximum diameter at A heating device characterized in that a ratio α/β to a diameter β is set in a range of approximately 0.7 to 1.3.