Permanent-magnet magnetothermal effect direct measuring instrument
One, technical field: the utility model relates to a kind of permanent-magnet magnetothermal effect direct measuring instrument.
Two, background technology: magnetic refrigeration is to be the Refrigeration Technique of operation material with the magnetic material, is that the magnetothermal effect by material self realizes freezing.Magnetothermal effect is a kind of inherent characteristic of magnetic material, and it is to be caused the change of material internal magnetic entropy by the variation of external magnetic field, and is accompanied by material heat absorption, heat release, reaches the refrigeration purpose with this.Near Curie temperature, it is maximum that the magnetothermal effect parameter of material reaches.General with the change of isothermal magnetic entropy | Δ S
M| or the adiabatic magnetization temperature becomes Δ T
AdTwo parameters are come the magnetothermal effect of exosyndrome material.The isothermal magnetic entropy becomes | Δ S
M| be the intrinsic properties of material, and the adiabatic magnetization temperature become Δ T
AdBe the apparent character of material, can intuitively reflect the refrigerating capacity of material, have more practical significance.
The method of measuring at present the material magnetothermal effect has two kinds of the direct method of measurement and the indirect methods of measurement.Measuring indirectly is magnetic field intensity and the specific heat that records the material different temperatures earlier, draws its isothermal magnetic entropy by Mike's Si prestige Equation for Calculating then and becomes Δ S
MBecome Δ T with the adiabatic magnetization temperature
AdDirectly measuring is to utilize temperature sensor directly to measure the temperature value of magnetic cooling material adiabatic magnetization front and back, thereby draws the method for the adiabatic magnetization temperature change Δ T of material.For the device that adopts in the direct measuring method, existing report provides the instrument in magnetic field etc. with electromagnetism magnetic field and pulsed magnetic field, but this instrument has following shortcoming: 1, the cost of equipment and operating cost height; 2, apparatus structure complexity, complex operation; 3, adopt electromagnetic field or pulsed magnetic field to realize changes of magnetic field, have relaxation time, influence the measurement of material magnetothermal effect parameter by the size that changes electric current.
Three, summary of the invention: the purpose of this utility model is for overcoming the deficiencies in the prior art, provide a kind of simple in structure, easy and simple to handle, operating cost is low, measurement data is true and reliable, the permanent-magnet magnetothermal effect direct measuring instrument of precision height, stable, good reproducibility.
The purpose of this utility model realizes in the following manner:
The utility model comprises constant temperature system, permanent magnetic field system, sample test bar, sample test bar mobile system, temperature measurement system, constant temperature system comprises the metal shell of sealing, in metal shell, be provided with compression mechanism device for cooling and semiconductor refrigerating heating combined equipment, in the effective temperature control area of constant temperature system, be provided with reference test bar and move the chamber, permanent magnetic field system is enclosed within reference test bar and moves outdoorly, and its magnetic field is uniform permanent magnetic field; The sample test bar is made with insulating material, and its top is provided with the sample chamber of band edge lid; Temperature measurement system is made up of temperature probe and computing machine, and temperature probe is located in the sample chamber, and its lead-in wire is drawn reference test bar by lead along the spill lead channels of reference test bar side, links to each other with computing machine; On the metal shell that moves chamber one end facing to reference test bar, have a hole for the discrepancy of sample test bar; Sample test bar mobile system by track, motor and be located on the track can orbital motion clamp constitute track and the corresponding setting of sample test bar access hole.
Above-mentioned permanent magnetic field system is to adopt poly-magnetic semi-closure magnetic Circuit Design, and (permanent magnet can be made fan-shaped, square, polygon with permanent magnet magnetic field system that permanent magnetic material (can be permanent magnetic materials such as NdFeB, SmCo system, SmFeN system) assembles.Multiple shapes such as that the shape of magnetic field work space can be done is circular, oval, square, polygon), its objective is to surveying instrument stable, permanent magnetic field uniformly is provided; Reference test bar moves the chamber and is made by metal tube, and adds between the permanent magnetic field system heat-barrier material is arranged, and not only can reduce thermal loss but also can avoid the influence of excessive temperature to the permanent magnetic material magnetic property; The sample chamber inwall is with heat-barrier material, or inside, sample chamber is designed to bilayer vacuumizes, to guarantee the good adiabatic condition of sample.
The utility model has the advantages that:
1, simple in structure, easy and simple to handle.The utility model adopts permanent magnet design and assembly field system, and to compare the magnetic field of permanent magnet system architecture simple, easy and simple to handle with pulsed magnetic field, cryogenic magnetic field.
2, operating cost is low, and is economical and practical.The permanent magnet magnetic field system that the utility model is designed, its magnetic field intensity is 1.4-2.0T, can reach the magnetic field intensity that the pulsed magnetic place can provide, but no longer needs electric energy in the test run process, save a large amount of electric energy, also saved the used liquid nitrogen of cooling coil in the pulsed magnetic field simultaneously.
3, measurement data is true and reliable, the precision height.The utility model, has been avoided the heat interchange of sample in magnetic history, thereby has been made the adiabatic temperature delta data of being surveyed accurate with heat insulator at the sample chamber inwall on the one hand.On the other hand, temperature probe of the present utility model is close to sample surfaces, and moves with sample, thereby can accurately record the temperature value before and after the sample magnetization, thereby obtains the adiabatic magnetization temperature variation of material.
4, stable, good reproducibility.The Nd-Fe-B permanent magnet field system of the utility model design, one, its magnetic field intensity value stabilization is constant, thereby can guarantee the repeatability of measurement data, two, this practical utility model adopts poly-magnetic semi-closure magnetic Circuit Design, the performance difference of different local used neodymium iron boron magnetic bodies has reduced the influence of demagnetizing field, improve the homogeneity in magnetic field effectively, guaranteed the stability and repeatability of test data from another point of view.
Four, description of drawings:
Fig. 1 is a structural representation of the present utility model;
Fig. 2 is the structural representation of permanent magnetic field system;
Fig. 3 is the structural representation of sample test bar.
Five, embodiment:, provide embodiment of the present utility model with reference to accompanying drawing.
The utility model comprises constant temperature system, permanent magnetic field system 3, sample test bar 4, sample test bar mobile system, temperature measurement system.Constant temperature system comprises the metal shell 18 of sealing, in metal shell 18, be provided with compression mechanism device for cooling and semiconductor refrigerating heating combined equipment, in the effective temperature control area of constant temperature system, be provided with reference test bar and move chamber 7, permanent magnetic field system 3 is enclosed within reference test bar and moves outside the chamber 7, and its magnetic field is uniform permanent magnetic field; Sample test bar 7 usefulness insulating material are made, and its top is provided with the sample chamber 5 of band edge lid 9; Temperature measurement system is made up of temperature probe 11 and computing machine 26, and temperature probe 11 is located in the sample chamber 19, and its lead-in wire is drawn reference test bar 4 by lead 12 along the spill lead channels of reference test bar side, links to each other with computing machine 26; On the metal shell 18 that moves chamber 7 one ends facing to reference test bar, have a hole for 4 discrepancy of sample test bar; Sample test bar mobile system by track 21, motor 23 and be located on the track 21 can orbital motion clamp 22 constitute, track 21 and the corresponding setting of sample test bar access hole, metal shell 18 can be the iron sheet box.
Permanent magnetic field system 3 comprises magnet yoke plate 13, permanent magnetic material 14.The magnet yoke plate is that thickness is the solid drawn tube of the mild carbon steel of 4-20mm or pure iron or forms required shape by low carbon steel plate or pure iron plate, permanent magnetic material is the high performance permanent magnetic materials of several different magnetic properties, for example: Nd-Fe-Bo permanent magnet material, permanent magnetic material is processed into the magnet group of the shape of design needs according to the magnetic circuit of design, every group of magnet is close to complete close-shaped magnetic closed hoop of wall energy composition in the yoke, and the magnetic property difference of the magnet that diverse location adopted, 1-15 group closed hoop is formed permanent magnetic field system, and its work space 19 is changeable according to designed magnetic circuit.
Semiconductor refrigerating heating combined equipment in the constant temperature system is stained with heating and cooling semiconductor chip 2 formations by the one side of L type metal (metals such as red copper, brass, stainless steel, silver, gold) plate 1 vertical plane; The center of the another side of L type sheet metal 1 vertical plane is being welded and is being slightly less than the reference test bar that red copper (metals such as brass, stainless steel, silver, the gold) pipe of magnetic field work space 19 makes by external diameter and moves chamber 7, permanent magnetic field system 3 is enclosed within reference test bar and moves outside the chamber 7, and be against L type sheet metal 1, making reference test bar move chamber 7 is in the magnetic field work space 19, and permanent magnetic field system 3 and L type sheet metal 1 and reference test bar move all to add between the chamber 7 heat insulator, as polyurethane foamed material, to prevent the magnetic property of temperatures involved permanent magnetic material.Below L type sheet metal 1 surface level, be close to a metal (metals such as red copper, brass, stainless steel, silver, gold) box 15, be provided with metal (metals such as red copper, brass, stainless steel, silver, gold) pipe 16 condensers of making in the box by thin skin, be connected with fluorochlorohydrocarbon in the pipe 16, by compressor 17 compression cycle refrigeration.Said structure (except that gas compressor) is installed in the iron sheet box 18, all slits closely knit filling of heat insulator therebetween, the front of iron sheet box 18 is left with reference test bar and is moved the identical circular hole of chamber 7 external diameters size, so that sample test bar 4 turnover reference test bars move chamber 7.The constant temperature system of having formed surveying instrument like this reaches the desired temperature range of test by compressor and heating and cooling semiconductor chip two-stage refrigeration (heating).(temperature range :-40-60 ℃)
Insulating material such as sample test bar 4 usefulness nylon or bakelite are made, and the sample chamber 5 of internal diameter for desired shape of design and size is processed on its top, and the termination inwall is threaded, and end cap 9 compresses sample along the screw thread precession.Sample chamber 5 inwalls are with heat insulator 6, have the aperture 20 of a φ 1mm in the sample chamber 5 away from the one side of opening termination, so that derive the lead 12 that connects temperature probe 11 lead-in wires, temperature probe 11 is positioned at sample chamber 5, its lead-in wire is derived by hole 20 by lead 12, spill lead channels along reference test bar 4 sides is drawn reference test bar 4, links to each other with computing machine 26;
Sample test bar 4 is fixed on the track 21 by stainless steel clamp 22, and clamp 22 can orbital motion under motor 23 drives, and clamp 22 drives sample test bars 4 orbital motions, and changes of magnetic field is realized in turnover magnetic field.The position in sample turnover magnetic field is by limit switch 24 controls, and limit switch 24 sticks at the relevant position at track 21 two ends.
The temperature probe 11 of temperature measurement system is positioned at sample chamber 5, and stick at the fritter smooth flat place on sample 10 surfaces with bonding agent, and it is mobile with sample 10, take all factors into consideration volume, response time and measuring accuracy, the utility model is selected the GW/GR2141 type platinum resistor temperature measuring element of German gloomy Xikang company for use.The lead-in wire of temperature probe 11 links to each other with computer system 26 by lead 12, by computer system 26 acquisition process test datas.
During measurement, at first temperature probe 11 usefulness bonding agents are sticked at the smooth flat place of sample 10, and together be positioned in the sample chamber 5, add one deck heat insulator 8 around the sample 10 again, screw sample chamber 5 top end covers 9 and compress sample 10, sample test bar 4 is placed in clamping on the stainless steel clamp 22, manually control starter motor 23, drive clamp 22 and move, sample 10 is sent to the correct position of permanent magnetic field system 3 along track 21.In second step, energized starts compressor 17 and heating and cooling semiconductor chip 2, opens Computer Automatic Test System simultaneously.The 3rd step, test parameter is set, comprise: sample number into spectrum, Range of measuring temp, probe temperature step-length (temperature interval of test), the 4th step, sample temperature is during near set lowest temperature, the closes compression refrigerator, temperature is because inertia can descend to such an extent that be lower than the design temperature lower limit, begin then to heat up gradually, the 5th step, sample temperature in the process that heats up, reach set temperature following in limited time, computing machine writes down this temperature value T1 automatically, automatically control starter motor 23 simultaneously, driving clamp 22 moves along track 21, clamp 22 moves drive sample test bar 4 and moves together, sample can be driven and shift out permanent magnetic field system 3, the final position of moving is by limit switch 24 controls, sample 10 shifts out magnetic field, if sample 10 has magnetothermal effect, sample 10 begins cooling, the minimum temperature point that computer automatic measuring system finds sample to drop to according to the design of test software programs, write down this temperature value T2, the 6th step, computer controlled automatic starter motor 23 drives clamp 22 and moves along track 21, and clamp 22 moves drive sample test bar 4 and moves together, sample can be driven shift-in permanent magnetic field system 3, the particular location that enters is by limit switch 25 controls.Wait for next measurement temperature spot, in the 7th step, sample 10 temperature continue to raise, and reach next probe temperature point, repeat for the 4th step, the 5th step, the operation of the 6th step.Measure temperature value T1, the T2 of a series of sample magnetization front and back, temperature data machine is as calculated handled like this, can be depicted under the certain magnetic field effect relation curve of magnetic refrigerating material temperature T 1 and thermal insulation of materials magnetization temperature variation Δ T, i.e. Δ T-T curve.