Background technology
Along with industry competition aggravation, stone material, engineering construction industry are strong day by day to the requirement that reduces cost, raises the efficiency, and domestic and international market rises rapidly to the demand of high-performance diamond instrument.
Make the existing several different methods of diamond tool.Every kind of method all is first with diamond and one or more metal dusts, also may be ceramic powders or organically adhesive powder mixing, then this mixture is become knot closely in pressurization or not pressure sintering.Wherein, adhesive powder bonds and controls diamond.Hot pressing and free sintering are the most frequently used manufacture methods, other then be of little use as methods such as high temperature insostatic pressing (HIP)s.
In powder metallurgy, metal dust should have good sintering reaction activity.Good sintering reaction activity means that metal dust can be at relatively low sintering temperature near solid density, or sintering reaches solid density and only needs very short sintering time.High sintering temperature can cause following major defect: the reduction of sintering mold life-span, adamantine degraded and high energy consumption.The required minimum sintering temperature of good sintering activity should be low as much as possible, preferably is no more than 850 ℃.Sintering activity can characterize with the relative density that obtains: in general, relatively sintered density reaches 96% or above being considered near solid density.
The primary factor that influences the sintering reaction activity is the composition of powder.Yet, owing to the reason of cost or for to the sintered body performance, the especially requirement of hardness, wearability etc., the component of powder is to change in too big scope.Influence second granularity that key factor is a powder of powder sintered activity, under the identical situation of other conditions, the sintering activity of thin powder obviously is better than thick powder.The important factor of another one is exactly the oxidation of powder surface, because powder size is thin, and the surface-active height, be exposed in the air, will be easy to take place oxidation, thereby form oxide skin(coating) at powder particle surface, and then the carrying out that stops sintering reaction, therefore reduced the sintering reaction activity of powder.
At present, using maximum Metal Substrate adhesive powders in the diamond tool is super-fine cobalt powder, and its granularity (is used Fisher sub-sieve sizer, FSSS) less than 7 μ m.Other metal dusts commonly used also have the mixture of fine metal powder, mixture as thin cobalt powder, copper powder, iron powder, nickel powder and tungsten-carbide powder, or thicker pre-alloyed powder (less than 40 μ m), the thick pre-alloyed powder of forming by iron, copper, nickel that makes as atomization.
From technical standpoint, use thin cobalt powder that diamond tool has been brought good result; But be to use cobalt that some shortcomings are also arranged: one of major defect is higher price of cobalt powder and strong price fluctuation, and simultaneously, cobalt is also under a cloud to have harm to environment.And at the mixed powder that uses thin metal dust during as adhesive powder, because the uniformity of mixed-powder has substantial effect to the mechanical performance of final instrument, the hardness of resulting agglomerate, intensity and abrasion resistance properties are all relatively low.When using thick pre-alloyed powder, generally need about 1100~1300 ℃ sintering temperature, under this temperature, tangible degraded can take place in diamond---and be so-called graphitization.
Summary of the invention
The objective of the invention is to adopt the chemical coprecipitation technique of slaine or metal hydroxides prepare a kind of with at least two kinds be selected from Fe, Co, Cu, Ni are base, in Mn, Ti, Sn, Mo, W, WC and the rare earth element as intensified element one or more have been added simultaneously, as La or Ce or Y, pre-alloyed powder.Contain the Fe that is not more than 80wt% in this powder, the Co of maximum 40wt%, the Cu of 80wt% and the Ni of 40wt% at most at most, and the M of maximum 8wt% and the RE of 0~5wt%, wherein, M represents one or more among Mn, Ti, Sn, Mo, W, the WC, and RE is a kind of of La, Ce in the rare earth element or both compounds, and other components in the powder are unavoidable impurities.
Pre-alloyed powder in the invention, its elementary particle size that adopts SEM mensuration preferably is no more than 10 μ m less than 15 μ m.Thinner powder size can guarantee that powder has bigger specific area, and for the pre-alloyed powder of same composition, and bigger specific area is the sign of high sintering reaction activity.
Pre-alloyed powder in the invention, the oxygen content that adopts noble gas infrared induction impulse method to measure is no more than 2%, preferably is no more than 1.2%.Oxygen content is no more than 2%, preferably is no more than 1.2%.The existence of oxygen all has harm to the sintering reaction of powder bending strength active and agglomerate, therefore needs the control oxygen content a lower level.
Pre-alloyed powder in the invention contains the rare-earth elements La that adds as additive, one or more the compound among the Ce.General, rare earth element has crystal grain thinning, scavenging material surface and interface, the absorption objectionable impurities, as effects such as oxygen and sulphur, can significantly improve the mechanical performance of the active and agglomerate of the sintering reaction of pre-alloyed powder, as bending strength etc., and to durability of diamond.
Pre-alloyed powder in the invention, based on its suitable component and special preparation technology, the pre-alloyed powder for preparing has good homogeneity of ingredients and enough sintering reaction activity, simultaneously suitable component can be kept so that the performance of agglomerate, particularly its hardness, bending strength, abrasion resistance properties and enough to the diamond hold, thus foregoing shortcoming in the manufacturing of diamond tool, avoided.
The present invention is achieved by the following technical solutions: in the salting liquid of the element that includes designed component, add a certain amount of precipitating reagent, the pH value of regulator solution fully staticly settles the complex salt sediment that obtains element after the reaction.Then sediment is heated at a certain temperature, making it decomposes becomes oxide.Again with oxide in reduction furnace, under certain atmosphere, reduction reaction takes place, oxide is reduced into required pre-alloyed powder.The reduction afterproduct carries out Passivation Treatment behind crushing and screening, last vacuum-packed.
The salting liquid of the element among the present invention can be the mixed solution of a kind of chloride solution, sulfate liquor, nitrate solution or these salt.
Precipitating reagent among the present invention can be alkali, carbonate, alkali and carbonate and oxalic acid.
The specific embodiment
The preparation of embodiment 1:Fe-Cu-Co-Mn-La pre-alloyed powder
This embodiment relates to by adopting oxalic acid to prepare pre-alloyed powder among the present invention as the reduction reaction of the oxalates compound of precipitating reagent and post precipitation.
90 ℃ and stir under, will contain 75g/l Fe, 43g/l Cu, 45g/l Co, 5g/l Mn, the sulfate of 3g/l La and chloride mixing salt solution join and contain 126g/l C
2H
2O
4H
2In the oxalic acid aqueous solution of O, adding ammoniacal liquor adjusting pH value is 4.5.Carry out 1 hour so that react completely.Like this, 82% Fe, 88% Cu, 95% Co, 48% Mn, 75% La just precipitate to mix the oxalates form.
Sediment is 7 up to filtrate pH, and does not have sulfate radical and Cl substantially by adopting the pure water filtration washing.With sediment 100 ℃ of dryings.
Adopt hydrogen as reducing atmosphere in reduction furnace above-mentioned sediment, reduced 6.5 hours down at 650 ℃, the reunion metal derby that obtains loosening, this product just obtain pre-alloyed powder behind crushing and screening, be designated as powder 1.
This powder is by 42.3% Fe, 25.7% Cu, 29% Co, 1.5% Mn, 1.5% La (these percentages only account for the metal part) and 0.83% O
2Form.Adopting SEM to measure and obtaining the powder particle average diameter is 6.7 μ m.
The preparation of embodiment 2:Fe-Cu-Sn-Ce pre-alloyed powder
This embodiment relates to by adopting oxalic acid to prepare pre-alloyed powder among the present invention as the reduction reaction of the oxalates compound of precipitating reagent and post precipitation.
90 ℃ and stir under, will contain 75g/l Fe, 40g/l Cu, 7g/l Sn, the sulfate of 1g/l Ce and chloride mixing salt solution join and contain 126g/l C
2H
2O
4H
2In the oxalic acid aqueous solution of O, adding ammoniacal liquor adjusting pH value is 4.5.Carry out 1 hour so that react completely.Like this, 82% Fe, 88% Cu, 55% Sn, 80% Ce just precipitate to mix the oxalates form.
Sediment is 7 up to filtrate pH, and does not have sulfate radical and Cl substantially by adopting the pure water filtration washing.With sediment 100 ℃ of dryings.
Adopt hydrogen as reducing atmosphere in reduction furnace above-mentioned sediment, reduced 7 hours down at 680 ℃, the reunion metal derby that obtains loosening, this product just obtain pre-alloyed powder behind crushing and screening, be designated as powder 2.
This powder is by 60.8% Fe, 35% Cu, 3.5% Sn, 0.6% Ce (these percentages only account for the metal part) and 0.91% O
2Form.Adopting SEM to measure and obtaining the powder particle average diameter is 7.2 μ m.
Embodiment 3: the sintering experiment of pre-alloyed powder
This example relates to be measured the sinterability of powder 1 of the present invention and powder 2.
Adopt method to measure the sinterability of powder: powder is placed the graphite jig that is of a size of 40mm * 5mm * 5mm, and pressure is 35MPa, different temperature sintering 3 minutes, measures the relative density of agglomerate, and the result sees table 1.
The relative density of table 1 sintered powder
The result shows that powder 1 and powder 2 can obtain higher sintered density under lower sintering temperature.Can not improve the relative density of powder 1 and powder 2 at sintering more than 850 ℃.
Embodiment 4: the mechanical performance of pre-alloyed powder
This example relates to the experiment to the mechanical performance of powder 1 of the present invention and powder 2.
Powder is placed the graphite jig that is of a size of 40mm * 5mm * 5mm, and pressure is 35MPa, different temperature sintering 3 minutes, measures the RockwellB hardness of agglomerate.The result sees table 2.
The mensuration of bending strength: the agglomerate of 40mm * 5mm * 5mm is placed directly on two bearings of the 30mm of being separated by, and the application of force in the middle of at interval is until sample fracture.The result sees table 3.
The hardness of table 2 sintered powder
The bending strength of table 3 sintered powder
Embodiment 5:La and Ce be not to containing the influence of diamond carcass
This example table is understood the influence of the interpolation of rare-earth elements La and Ce to the mechanical performance of the sintering gained agglomerate of powder 1 and powder 2.
According to the method among the embodiment 1, in powder 1, add different content La, by whether sneaking into diamond, respectively with the powder that makes in graphite grinding tool, under the 35MPa, 850 ℃ sintering temperatures 3 minutes.The result sees table 4.
Table 4La is to powder 1 sintering machinery Effect on Performance
?La(wt%) |
0 |
0.75 |
1.5 |
2.25 |
3 |
?HRB |
98 |
99.5 |
100.5 |
101 |
102 |
Bending strength (MPa) (not containing diamond) |
521 |
563 |
631 |
692 |
667 |
Bending strength (MPa) (containing diamond) |
498 |
669 |
622 |
619 |
594 |
As seen, along with the increase of the La content trend by slow rising, bending strength reaches maximum along with the increase of the La trend by obvious rising when 2.25wt% for the hardness of diamantiferous agglomerate not.And for containing adamantine carcass, situation is different, its high-flexural strength is 0.75wt%, subsequently along with the increase of La content, the bending strength that contains the diamond carcass begins to be lower than the bending strength that does not contain the diamond carcass, but still is higher than the carcass that does not add La, this explanation, La be added on remarkable reinforcement in conjunction with the performance of machine the time, also improved metal matrix and adamantine adhesive property significantly.
According to the method among the embodiment 2, in powder 2, add different content Ce, by whether sneaking into diamond, respectively with the powder that makes in graphite grinding tool, under the 35MPa, 850 ℃ sintering temperatures 3 minutes.The result sees table 5.
Table 5Ce is to powder 1 sintering machinery Effect on Performance
?Ce(wt%) |
0 |
0.3 |
0.6 |
0.9 |
1.2 |
?HRB |
99 |
99 |
100 |
100.5 |
101 |
Bending strength (MPa) (not containing diamond) |
573 |
604 |
675 |
732 |
713 |
Bending strength (MPa) (containing diamond) |
483 |
534 |
619 |
672 |
648 |
As seen, the hardness of agglomerate is along with the increase of Ce content remains unchanged substantially, slightly rises, and bending strength reaches maximum along with the increase of the Ce trend by obvious rising when 0.9wt%.
Because rare earth element has crystal grain thinning, scavenging material surface and interface, and their high activity can reduce the influence of harmful elements such as oxygen, sulphur, thereby the interpolation of La and Ce can significantly improve the bending strength of agglomerate.
Because mainly by the porosity decision, rare earth element and compound disperse thereof are distributed in the matrix hardness of agglomerate, play the pinning effect, suppress distortion, can cause agglomerate hardness slightly to improve.
Embodiment 6: rare earth element is to the influence of diamond tool cutting performance
This example table is understood the influence of the interpolation of rare-earth elements La and Ce to the cutting performance of the powder diamond saw blade that sintering obtains under the situation of other term harmonizations in the invention.
Press in the example 1 method, add the La of different content in powder 1, after diamond particles mixed, hot pressed sintering obtained diamond saw blade.And carrying out actual sawing experiment, the result sees table 6.
Cutting index Z in the table is defined as in the unit interval, under the condition of unit tool wear weightlessness, the size of excision stone material amount.Under the unit wear weight loss condition, the stone material of excision is many more in the unit interval for the big more specification tool of Z.
Table 6La is to the influence of cutting performance
La(wt%) |
0 |
0.75 |
1.5 |
2.25 |
3 |
Cut speed (cm
2/min)
|
73 |
78 |
84 |
89 |
81 |
Cutting index Z |
32.3 |
33.4 |
35.2 |
34.1 |
33.7 |
Press in the example 1 method, add the La of different content in powder 1, after diamond particles mixed, hot pressed sintering obtained diamond saw blade.And carrying out actual sawing experiment, the result sees table 7.
Table 7Ce is to the influence of cutting performance
Ce(wt%) |
0 |
0.3 |
0.6 |
0.9 |
1.2 |
Cut speed (cm
2/min)
|
73 |
79 |
87 |
92 |
83 |
Cutting index Z |
35.6 |
36.6 |
37.5 |
36.2 |
35.8 |
By table 6, table 7 as seen, add rare earth element after, the cutting speed of diamond saw blade and cutting index all are better than not containing the diamond saw blade of rare earth, and the saw blade that contains the Ce element more has superiority.
Embodiment 7: other pre-alloyed powders according to the invention
According to the method for embodiment 1-2, with alkali such as NaOH, carbonate such as NH
4HCO
3, Na
2CO
3, alkali and carbonate and oxalic acid etc. are precipitating reagent, can similarly prepare the pre-alloyed powder of Fe-Cu-Co-M-RE.Table 6 has provided the overview of these powder, and behind 850 ℃ or following temperature sintering, agglomerate has the bending strength that is not less than 550MPa and is not less than 80HRB hardness.All these compositions all fall into compositional range of the present invention and so on.
Table 8 is according to other compositions of the present invention
Powder |
Fe (%) |
Cu (%) |
Co (%) |
Ni (%) |
Sn (%) |
Mn (%) |
RE (%) |
Particle size (μ m) |
Oxygen content (%) |
3 |
59.5 |
26 |
|
|
3 |
1 |
0.5 |
6.1 |
1.03 |
4 |
80 |
|
18 |
|
|
1.5 |
0.5 |
8.2 |
1.14 |
5 |
32.4 |
41.2 |
17 |
2.6 |
3.8 |
1 |
2 |
7.8 |
0.96 |
6 |
20.3 |
39.7 |
|
35 |
4 |
|
1 |
7.7 |
0.87 |
7 |
14 |
56 |
18.8 |
|
7.5 |
1.5 |
2.2 |
7.0 |
0.85 |
8 |
15 |
32 |
35.5 |
8.8 |
5 |
1.2 |
2.5 |
8.5 |
0.72 |
9 |
28.3 |
40 |
25.7 |
|
4.3 |
|
1.7 |
7.5 |
0.78 |
10 |
|
68 |
|
30.4 |
|
|
1.6 |
5.5 |
0.62 |