JPH11201823A - Flying particle measurement device - Google Patents

Abstract

(57) [Summary] To enable measurement of temperature and velocity of a single particle in flight corresponding exactly to a particle attached to a substrate. A single particle feeder (40) is provided in a hot particle injection device.
And only a single particle is jetted. Further, a trigger signal generator 50 for detecting the passage of the particles by a plurality of sensors s1 and s2 and outputting a trigger signal based on the detection signals is provided. The trigger signal generator 50 detects that the particles 20
At the point in time when it arrives in front of the wavelength high-speed shutter camera 11, the camera 11 is triggered and the temperature and speed of the particles are measured. Therefore, the temperature and velocity of only a single particle can be reliably measured without measuring the suspended particles. In addition, a movable slit 90 interlocked with the output of the trigger signal generator 50 is provided so that only the measured particles adhere to the substrate. Therefore, the correspondence between the measured particles and the attached particles becomes more accurate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring apparatus for measuring high-temperature flying particles injected from a plasma gun or the like in a thermal spraying technique. In particular, the present invention relates to a measurement apparatus capable of measuring a physical quantity such as a temperature and a velocity of a single particle in flight which completely corresponds to one attached particle, thereby measuring a relationship between a particle attachment state and a physical quantity in flight.

[0002]

2. Description of the Related Art Thermal spraying technology generally consists of a series of processes of charging material powder or fine particles to a heat source, heating, accelerating, melting, colliding with a substrate, flattening, solidifying, and laminating. Made in milliseconds. The surface coating characteristics are strongly affected by the size of particles ejected from a plasma gun or the like, the flight speed, and the temperature. In order to improve the coating characteristics, it has been conventionally required to clarify the relationship between the size, temperature and speed of each flying individual particle and the form of adhesion to the substrate. For that purpose, it was necessary to measure not a particle group or a particle bundle having a distribution in physical quantities such as temperature and velocity, but a specific one particle having a determined temperature and a determined velocity and its adhesion characteristics. .

[0003] Conventionally, as an apparatus for measuring individual particles in flight at a high temperature, a Pyrometer system for monitoring the
particle impact on a Substrate during a plasma sp
There is rayproces (Meas.sci.Tecnol.5 (1994)). In this apparatus, a minute hole is provided in a flight path of a high-temperature particle group, and the temperature of a particle passing therethrough and a particle adhering to a substrate are measured by two two-color radiation thermometers. The relationship between the state of particles (temperature, velocity) during flight and the state of adhesion on the substrate is determined from the spectral intensity ratio of.

[0004]

However, in the above-mentioned apparatus, a single particle is taken out by providing a minute hole in a flight path without taking a method of image measurement in order to take out a single particle. I have. However,
The probability that only a single particle passes through the micro-hole is extremely small, and there is a great risk that a cluster or a group of several particles will be regarded as one particle and measured. Correspondence was not always possible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. In the measurement of flying particles in the thermal spraying technique, instead of selecting and measuring one from a population of particles in flight, measurement is performed. On the contrary, paying attention to the particle injection method which is the first process, devising a single particle supply means capable of surely inputting the fine particles one by one, and applying the same, the measured particles and the attached particles are applied. It is an object of the present invention to provide a flying particle measuring device which is surely the same.

[0006]

In order to achieve this object, a flying particle measuring apparatus of the present invention measures particles in flight at least at two wavelengths at the same time, and the size of the measured data is larger than that of the measured data. In a flying particle measuring apparatus for measuring physical quantities such as velocity, temperature, etc., a single particle supply means for supplying particles one by one, and a particle injection means for applying a predetermined temperature to the supplied single particles and injecting the particles A first particle detection unit that detects passage of particles in a flight path of the particles ejected by the particle ejection unit; a trigger signal generation unit that generates a trigger signal based on a signal of the first particle detection unit; , In synchronization with the trigger signal, the emitted light intensity of the flying
It is characterized by comprising second particle detecting means for measuring by wavelength and physical quantity calculating means for calculating a physical quantity of the flying particle based on data obtained from the second particle detecting means.

[0007]

The single particle supply means sends out the particles one by one to the supply path by an extrusion method or the like. The sent single particles are sent to the particle ejecting means via the supply path. The single particles sent to the particle ejecting means are melted at a predetermined temperature (high temperature) and are ejected at a high speed by the ejecting means. The molten particles jetted at high speed fly and adhere to the substrate. In the middle of the flight path of the particles, the first particle detection means detects the passage of the molten particles and sends the passage timing to the trigger signal generation means. The trigger signal generation means sends a trigger signal for instructing the second particle detection means to start measurement to the second particle detection means after delaying a predetermined time in order to consider the flight time of the particles. The second particle detecting means that has received the trigger signal measures the emission light intensity of the flying particle using two wavelengths in synchronization with the trigger signal. The physical quantity calculating means calculates the physical quantity serving as basic data of the flying particles, such as the temperature, velocity, and mass of the flying particles, based on the data obtained from the second particle detecting means.

As is apparent from the above description, the flying particle measuring apparatus of the present invention supplies single particles one by one, checks the passage of each individual particle by the detecting means, and measures them. Since the trigger signal is used, it is possible to reliably measure only a single particle in flight, and to reliably obtain the correspondence between the measured particles and the adhesion characteristics of the particles attached to the substrate.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an example of the present embodiment. A flying particle measuring apparatus according to the present invention includes a single particle supply device 40 as a single particle supply unit, a plasma gun 30 as an injection unit, and a supply of single particles. S1, a sensor s2 as first particle detecting means for detecting passage of flying particles in the flight path, a trigger signal generator 50 for generating a trigger signal, and a radiant light intensity of particles in flight of 2
It is composed of a two-color high-speed shutter camera 11 as a second particle detecting means for measuring by wavelength, and a computer 70 for calculating physical quantities such as temperature and speed from electric signals or image data obtained by them.

As shown in detail in FIG. 2, the single particle feeder 40 includes a stepping motor 40c, a stepping motor driver 40d, a plunger 40b which moves back and forth by the rotation of the stepping motor 40c, a passage for the fine particles and a storage location. And a syringe pipe 40a having an inner diameter of several tens μm to several hundred μm. The syringe pipe 40a is a partly transparent particle supply pipe 30 reaching the plasma gun 30.
a. Stepping motor driver 40
The number of pulses output from d is the size of the particles to be supplied and the resolution of the plunger (movement amount per pulse)
For example, the control resolution of the plunger 5
When supplying 50 μm particles in μm, particles are supplied approximately every 10 pulses. Various particles such as zirconia, alumina, and molybdenum alloy are selected as the particles depending on the target surface modification such as wear resistance and lubricity.

The particles extruded by the stepping motor 40c and the plunger 40b pass through the particle supply pipe 30a and are supplied to the plasma gun 30.
In the meantime, the passage of the particles is detected by an optical sensor s1 provided in the particle supply pipe 30a, for example, using an optical fiber, and a supply signal is sent to the trigger signal generator 50.

The particles supplied to the plasma gun 30 are ionized by a plasma arc into a gas (for example, argon gas), which is drawn into a plasma that has reached several thousand degrees, and is instantaneously molten or semi-molten. The state is reached, and the liquid is ejected toward the substrate 80 at a speed of several m / sec to several tens m / sec per second. Since the ejected particles 20 are in a high temperature state, they fly while emitting radiation light according to the particle temperature, and become attached particles 22 on the substrate 80.

An optical sensor s2 provided on the flight path
When the flying particle 20 passes in front of it, it senses the emitted light of the particle and generates a pulse-like passing signal as a trigger signal generator 5.
Send to 0. The trigger signal generator 50 has a timer circuit 51 as shown in FIG. 3, and sends a trigger signal 52 to the two-color high-speed shutter camera 11 with a delay of a predetermined delay time t ₁ . The predetermined delay time t ₁ is the injection speed V
Is the time from the passage of the high-temperature particles ejected in front of the sensor s2 to the front of the two-color high-speed shutter camera 11, and t ₁ = L0 / V. For example, when the separation distance L0 is 2 cm and the injection speed is 100 m / sec, the delay time is 0.2 msec. These trigger signals 52 are input to an AND unit 55, and only when the sensor s1 detects the passage of flying particles, a trigger signal 53, which is an imaging command, is sent to the two-color high-speed shutter camera 11 as the trigger signal 53. .

In some cases, the jet flow injected from the plasma gun contains foreign matter or impurities in the injection device or in the supplied gas. In order to prevent malfunction due to foreign matter or impurities, the trigger signal from the sensor s1 and the sensor s2 is configured such that only the first trigger signal after reset is valid by the RS flip-flop 56, and the signal is erroneously floated. Even if particles or the like are subsequently detected, the trigger signal 53 is not output, and the suspended particles and the like are not measured.

When a trigger signal 53, which is an imaging command, is sent to the two-color high-speed shutter camera 11, the image measurement system shown in FIG.
Thereby, an image of the flying particles 20 arriving in front of the lens 60 is captured, and a video signal is output to the A / D converter 12. The digital signal from the A / D converter 12 is transmitted to the CPU 1
0, the image memory 141 of the RAM 14,
142. The image memory 141 is a memory for storing a light intensity image of a wavelength r, and the image memory 142 is a memory for storing a light intensity image of a wavelength g. ROM13
Is formed a program area 131 in which a program for executing the method of the present embodiment is stored. Further, the program may be stored in a storage medium 15 such as an FD, and may be stored in the RAM 14 from the medium 15 to execute the program.

Next, FIG. 5 shows a processing procedure of the CPU 10.
The processing procedure will be described with reference to the flowchart of FIG. In step 100, the two-color high-speed shutter camera 11
And an image of the flying particles 20 is captured by the two-color high-speed shutter camera 11. Next, in step 102, data output from the A / D converter 12 is sequentially input and stored in the image memories 141 and 142. For example, a light intensity image at a wavelength r is schematically shown in FIG. The line in FIG. 6A is an iso-light intensity curve, and one particle a1 is imaged. An image as shown in FIG. 6A is obtained in the same manner for the wavelength g.

Next, in step 104, FIG.
In the light intensity image of (a), an image of one particle is cut out. This is because the light intensity image of the particles is substantially concentric, and by matching with a preset concentric pattern, a region X indicated by a broken line in FIG. 6A is cut out. The same applies to the light intensity image of the wavelength g. If the light intensity image of one cut-out particle is represented by the distribution of light intensity I along the U-axis direction passing through the center, the light intensity image has a substantially normal distribution as shown in FIG.

Next, at step 106, the light intensity I
A frequency is calculated. First, as shown in FIG. 6B, pixels of light intensity I ≧ threshold Th are extracted. As a result, noise components can be removed. The total number of the extracted pixels is defined as n _r and _ng . Next, in the extracted pixels, the number n _r (m), n _r (m) of pixels belonging to each class I _r (m), I _g (m) of the light intensity I is calculated. Next, relative frequencies R _r (m) and R _g (m) in each class are calculated by the following equations.

[0019]

R _r (m) = n _r (m) / n _r (1)

R _g (m) = _ng (m) / _ng (2)

Next, at step 108, the cumulative relative frequencies L _r (k) and L _g (k) are calculated by the following equation.

[Number 3] _{L r (k) = Σ m} = 1 k R r (m) ... (3)

Equation 4] _{L g (k) = Σ m} = 1 k R g (m) ... (4) In addition, (3), (4) the class from a less-class light intensity side I _r (k), It means the addition of the relative frequency up to I _g (k).
However, the classes I _r (1) and I _g (1) of m = 1 correspond to the light intensity Th.

That is, the cumulative relative frequency L _r (k) means the ratio of the pixels whose light intensity is equal to or smaller than I _r (k) and equal to or larger than the threshold Th to the number n _r of pixels equal to or larger than the threshold Th in the light intensity image of wavelength r. . The same applies to the cumulative relative frequency L _g (k). Cumulative relative frequency L _r for light intensity classes I _r (k) and I _g (k)
FIG. 7 shows, for example, (k) and L _g (k). The image with the wavelength r has a lower relative light intensity than the image with the wavelength g, and the cumulative relative frequency reaches 100%.

Next, the cumulative relative frequency _{L r (k), L g} (k) and a common variable L of the same value, the cumulative relative frequency L of each light intensity upper limit _{I r (k), I g} (k ) Let A (L) and B (L) denote the pixel regions having the above light intensity. Also, a common area of the pixel area is C (L). When the common variable L is sequentially increased, the common area C (L) decreases. So common variables
L is sequentially increased, and the value of the common variable L at which the common area C (L) takes the minimum value larger than 0 and the pixel address of the common area C (L) are determined. These processes are performed in step 110
It is executed by the repetition calculation in to.

Since the emitted light of the high-temperature particles has a predetermined spectrum according to the temperature distribution, the emission light at wavelengths r and g
In the two images, the light intensity distributions shown in FIG. 6B do not completely match, and the light intensity points are slightly shifted. FIG.
As shown in (c), the pixel regions A (L) and B (L) gradually decrease around the center point when the cumulative relative intensity L is increased. Therefore, the common area C (L) also gradually decreases. When the cumulative relative frequency L is equal to or more than a certain value, the common area C (L) disappears, and C (L) becomes the minimum area C0 at a value one stage before the value. If the center points of the two images completely match, the cumulative relative frequency
At L = 100%, C (L) takes the minimum area C ₀ .

Next, in step 116, in the minimum area C ₀ , the center of gravity is calculated using the light intensity as the mass density, and the center of gravity is determined as the particle position G (X ₀ , Y ₀ ). If the minimum area _C0 is one pixel, the particle position determines the particle position. Next, each wavelength r, g
The light intensity I _0r , I _{0g at} the particle position is obtained from the image of FIG. The light intensities I _0r and I _0g are corrected by the lens sensitivity of the camera 11, the shutter speed, etc., and the intensity of the emitted light of the particles is corrected.
_Find S _0r and S _0g . Using the following _radiated light intensities S _0r and S _0g , the temperature T is calculated by the following equation.

[0025]

S _0r / S _0g = (g / r) ⁵ · EXP [b (1 / g−1 / r) / T] (5) where b is a constant. As is well known, this equation can be obtained by taking the ratio of Planck's equation for radiation at wavelengths g and r.

When the cumulative relative frequency L is changed, the maximum temperature, the minimum temperature, and the average temperature in the common area C (L) change as shown in FIG. That is, when the cumulative relative frequency L = 0, the common area C (L) is substantially equal to all images equal to or larger than the threshold Th. Therefore, the temperature obtained from the light intensity of each pixel is widely distributed from the maximum temperature to the minimum temperature. However, when the cumulative relative frequency L increases, the common area C (L) decreases. That is, the common area C (L) does not sequentially include a portion where the light intensity is low and a portion where the light intensity is high in the light intensity image of the wavelength g and the light intensity image of the wavelength r. Therefore, as shown in FIG. 8, the maximum temperature in the common area C (L) decreases and the minimum temperature increases. The convergence value of the temperature is the particle temperature to be obtained. Regarding the position, as the common area C (L) is wider, the particle position becomes more ambiguous, and the converged area of the common area C (L) becomes C ₀ . Thus, the position and temperature of the particles can be accurately determined.

In the above embodiment, the cumulative relative frequency L is changed in a direction to increase, but the cumulative relative frequency L is changed to 100%.
May be changed in the direction of decreasing. In this case,
The common area C (L) gradually expands from zero. Therefore, when a value other than 0 is obtained, it becomes the minimum common area C ₀ .

The speed of the particles can be obtained by multiple exposure at minute time intervals τ or by capturing light intensity images of the particles in a plurality of image memories. FIG. 6D is a schematic diagram similarly photographed τ hours later, and shows that the particles have moved rightward. About this image,
By the above-described method of obtaining the common area C (L), the center of gravity G (X ₁ , Y ₁ ) having the light intensity after τ hours as the mass density is finally calculated, and G (X ₀ , Y ₀ ) is calculated. The moving distance d is further obtained, and the moving speed of the particles is obtained from d / τ.

Further, the flying particle measuring apparatus of the present invention is provided with a movable slit 90 which is a passing particle selecting means which opens and closes in conjunction with the trigger signal generator 50 in front of the substrate 80. As described above, the jet flow jetted from the plasma gun 30 may contain foreign matter or impurities in the plasma gun 30 or in the supplied gas, and these suspended particles adhere to the substrate 80. There are cases. In order to avoid these erroneous measurements, as shown in FIG. 3, the trigger signal generator 50 sends the trigger signal 53 to the movable slit driver 5.
4, the movable slit 90 is opened for a predetermined time, and only the measurement particles are allowed to pass therethrough so that the floating particles do not adhere to the substrate 80. Therefore, the flying particle measuring apparatus of the present invention reliably measures only a single particle in flight and attaches only the measured particle to the substrate 80.
The correspondence between physical quantities such as temperature and velocity of flying particles and adhesion characteristics such as adhesion force of the adhesion particles can be taken.

In the above embodiment, the detection signal from the sensor s1 is used as a pre-trigger signal for preparing the shutter for driving the two-color high-speed shutter camera 11, but if the shutter signal can be driven only by the trigger signal 53, The sensor s1 that outputs the pre-trigger signal may not be provided. Further, by providing the movable slit 90, the flying particles to be measured and the particles adhering to the substrate 80 can be made to correspond with high accuracy. However, in the case where there are no noise particles other than the particles to be measured. The movable slit 90 need not be provided.

While one embodiment of the present invention has been described above, various other modifications are possible. For example, in the present embodiment, the single particles are supplied one by one by driving the plunger with the stepping motor.
Any type of actuator can be used for a motor or the like as long as the system can be controlled with a resolution smaller than the particle size.

For example, as a first modification, as shown in FIG. 9, a catapult system using a piezoelectric element may be employed.
A needle 40h for extruding particles is attached to one end of the laminated piezoelectric element 40e, and the other end is fixed to a fixed base 40f. High voltage (approximately 100V) to the piezoelectric element 40e
Is instantaneously applied to the needle 40h for about several tens μm to several hundred μm.
Are extruded, and momentum is given to the particles 2. The particles 2 given the momentum are ejected to the particle supply pipe 30a and supplied to the plasma gun 30 by the gas flow 40g. In the figure, E represents a power source, SW represents a switch, r represents a resistance for adjusting the rising speed of the displacement curve in FIG. 10, and is variously selected according to the mass of the particle. A few hundred kΩ is appropriate for adjusting the decay time.

As a second modification, the stepping motor 40c in FIG. 2 may be replaced with a piezoelectric element 40e, the stepping motor driver 40d with a high-voltage power supply E, and the plunger 40b with a needle 40h. Again,
As in the catapult system shown in FIG. 9, only the particle 2 at the forefront gains momentum, so that the particle 2 is repelled by the piezoelectric element 40e to the particle supply pipe 30a, and the gas flow 4
0 g is supplied to the plasma gun 30.

In the present embodiment, the two-color high-speed shutter camera 11 is used as the second particle detecting means. The temperature may be obtained from the intensity ratio of the pulsed electric signal using a radiation thermometer.

Further, in this embodiment, when obtaining the velocity of the particles, double exposure or micro exposure with a small delay time τ is used.
The moving distance was obtained from the image data of one sheet, and the speed was calculated. However, the real center corresponding to the center of gravity G (X ₀ , Y ₀ ) related to the light intensity obtained in the first image measurement, the sensor s2, and the center of the image was obtained. distance L ₀ between the position of, and Sense s2 can be determined from the delay time t to a trigger from the detection of the passage of particles 2 Iroshiki fast shutter camera 11. That is, as shown in FIG. 11, the particle movement distance L ₁ (= L ₀ ± X ₀ ) for t seconds is newly calculated from the separation distance L ₀ and the center of gravity G (X ₀ , Y ₀ ). And L ₁
The speed may be accurately obtained from / t.

In this embodiment, plasma spraying using a plasma gun has been described as an example. However, arc spraying, in which a voltage is applied to two sprayed wires and sprayed with compressed air or the like while being melted, or gas spraying is performed. -Applicable to other thermal spraying techniques such as thermal spraying.

[0037]

As is clear from the above description, according to the flying particle measuring apparatus of the present invention, one of the thermal spray techniques can be used.
For the measurement of flying particles, 1
Instead of selecting and measuring individual particles, a single particle supply means capable of surely feeding particles one by one was used. Further, the passage of the particles supplied by the single particle supply means is detected by a particle detection sensor, and a trigger signal which is a final measurement command signal is generated. Therefore, only a single particle can be reliably measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a flying particle measurement apparatus according to one embodiment of the present invention.

FIG. 2 is a configuration diagram showing a single particle feeder in the apparatus.

FIG. 3 is a block diagram showing a trigger signal generator of the device.

FIG. 4 is a block diagram showing a configuration of a computer of the apparatus.

FIG. 5 is a flowchart showing a processing procedure of a CPU of the apparatus.

FIG. 6 is an explanatory diagram for explaining a measurement method according to the embodiment.

FIG. 7 is a characteristic diagram showing a change characteristic of a cumulative relative frequency with respect to light intensity.

FIG. 8 is a characteristic diagram showing a change characteristic of a common area and a temperature with respect to a change of a cumulative relative frequency.

FIG. 9 is a configuration diagram showing a modified example in which a piezoelectric element is used for a single particle supply device.

FIG. 10 is a characteristic diagram showing a displacement curve of the piezoelectric element.

FIG. 11 is an explanatory diagram showing another method for obtaining a particle velocity in a modification of the present embodiment.

[Explanation of symbols]

 Reference Signs List 10 CPU 11 Two-color high-speed shutter camera 20 Flying particle 30 Plasma gun 40 Single particle feeder 50 Trigger signal generator 60 Objective lens for measurement 70 Calculator 80 Substrate 90 Movable slit 141, 142 Image memory

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroyuki Mori 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Yoshihiro Oishi 41, Oji, Nagakute-cho, Aichi-gun, Aichi Prefecture Yokomichi, Toyota Toyota Central Research Laboratory Co., Ltd. (72) Yasuhiko Suzuki Aichi 41, Chukku-Yokomichi, Nagakute-machi, Aichi-gun

Claims (1)

[Claims] 1. A flying particle measuring apparatus for simultaneously measuring particles in flight with at least two wavelengths and measuring physical quantities such as size, speed and temperature from the measured data. Single particle supply means for supplying; a particle ejection means for applying a predetermined temperature to the supplied single particle to eject the particles; and detecting passage of particles in a flight path of the particles ejected by the particle ejection means. A first particle detecting means for generating, a trigger signal generating means for generating a trigger signal based on a signal of the first particle detecting means, and a radiant light intensity of the flying particles of two wavelengths synchronized with the trigger signal. Based on the second particle detecting means measured by the following, and data obtained from the second particle detecting means,
And a physical quantity calculating means for calculating a physical quantity of the flying particles.