CN1200125C - Pressure casting method for controllable volume percent SiCp/Al composite material - Google Patents

Abstract

The present invention relates to a pressure casting preparation method of controllable volume portion SiCp/Al composite material, which relates to a new pressure casting method and is mainly applied to preparation of particle reinforced metal composite material. The traditional pressure casting technology is difficult to control the volume portion of reinforced bodies in composite material. The method comprises the steps that SiCp particles and aluminium powder are mixed to prepare mixed powder; the mixed powder is prepared into a pre-cast block; a secondary pressure application method is used for pressure casting of the SiCp/Al composite material. The SiCp/Al composite material has the advantages of low volume portions (less than 30%), strong plasticity, etc.; the extrusion ratio of the SiCp/Al composite material can be more than 36: 1 at the temperature of 300 DEG C.

Description

The pressure die casting preparation method of controlled volume umber SiCp/Al matrix material

Technical field: the present invention relates to a kind of pressure die casting novel method, mainly is the preparation method who is applied to particles reiforced metal-base composition.

Background technology: the SiCp/Al matrix material can be given full play to Al and SiC particle advantage separately, and composition can design, SiCp/Al compares with matrix alloy has excellent mechanical property and physicals, have high specific tenacity and specific modulus, good anti-fatigue performance, low thermal expansivity and satisfactory stability, and the material anisotropy is little, with low cost, can use traditional deformation method easily and carry out secondary processing, be a kind of advanced material with broad prospect of application.Since coming out, be subjected to Materials science and the engineering Application Areas is paid attention to greatly always, through the development over nearly more than 20 years, the SiCp/Al matrix material is at present as a kind of important advanced material, and part replaces traditional metallic substance and at aerospace industry, automotive industry, Electronic Packaging and sports apparatus etc. the higher field of material performance requirement used.The price of SiCp/Al matrix material, quality stability are to hinder the principal element of its widespread use always.Given this, many investigation of materials persons are devoted to the preparation technology's of SiCp/Al matrix material research, efficient in development, save time, less energy-consumption, equipment are simple, can realize being similar to and obtain many achievements aspect the processing method of no surplus moulding.Relatively the technology of preparation particles reiforced metal-base composition commonly used has powder metallurgy, pressure die casting, stirring casting, spontaneous infiltration and is total to spray deposition technology etc. at present.Stirring casting technology is a kind of commonly used, lower-cost method, equipment used technology is simple relatively, do not need main equipment, can carry out ingot casting and the production of shape material, can carry out conventional secondary processing, be suitable for scale operation, weak point is that particle size usually can not be less than 5 μ m, also be involved in gas during stirring easily, the finished product of manufacturing easily has pore, and size distribution is inhomogeneous.The pressure casting process characteristics are to require lower to matrix metal and enhancing body wettability, can realize local the enhancing, and temperature controlling is got rid of surface reaction between particle and the liquid aluminium alloy during by infiltration, the infiltration time is short, the molten metal cooling is fast, strengthen the body even particle distribution, porosity is low; Its limitation is that the porosity and the aperture of prefabricated component is difficult to control, and SiC particle volume umber controlled range is little.Powder metallurgical technique is made temperature and is lower than casting, and the surface reaction that Yin Gaowen causes is few, and SiC particle volume umber is regulated arbitrarily, and ratio is accurate, and control is convenient, strengthens body and is evenly distributed, and is not prone to segregation and poly-partially, can adopt any alloy as matrix; Shortcoming is a complex process, and all must carry out under sealing, vacuum or protective atmosphere, equipment and material cost height; production cycle is long; the workpiece shape and size have certain limitation, the hole height, and the hot pressing ingot must improve density through viscous deformation such as extruding, forgings.Spontaneous infiltration is that suffered capillary force permeates product density height when contacting with prefabricated component by molten of metal; But the price of spontaneous infiltration technology is still very high, because this arts demand carries out under higher relatively temperature, and rate of permeation is lower, also has surface reaction simultaneously, reduces the performance of material.Spray co-deposition process speed is fast, sedimentation velocity can reach 4～10Kg/min, can obtain bigger blank, technological process is continuous, be convenient to realize automatization,, increased the solid solubility of alloying element owing to use flash set technology, the segregation on a large scale and the grain coarsening of metal can be inhibited, there is not poly-partially phenomenon in no interface reaction transition layer between enhanced granule and matrix, and the interface is in conjunction with being mainly mechanical bond, avoid matrix material generation surface reaction, surface reaction is controlled fully, strengthens body and is evenly distributed, and can obtain tiny non-equilibrium microstructure, and the particle add-on can control and adjust at any time, strengthens body and mixes with matrix fully, evenly; But also there are many problems in this novel method, starting material occurring is taken away and is deposited on the first-class phenomenon of equipment wall and lose bigger by air-flow, also has the high and easy situation of loosening that occurs of matrix material void content, the volume percent that particularly strengthens body is difficult to raising etc., be still waiting further solution, the one-time investment of equipment is very big in addition, is difficult to promote the use of.It is cheap that the SiC particle enhanced aluminum-based composite material has the prices of raw and semifnished materials, characteristics such as good combination property, research and use more, pressure casting process is one of its most frequently used preparation technology, but pressure casting process matrix material volume umber height usually greater than 40%, is difficult to carry out viscous deformation, the plastic working difficulty has limited the range of application of the SiCp/Al matrix material of pressure die casting preparation.The SiCp/Al matrix material of the preparation of pressure die casting at present is mainly used in the electronic package material field, the key that to increase its volume parts controlled range be the broadened application scope, but traditional pressure casting process is difficult to strengthen in the control matrix material volume parts of body.At present, the research for preparing enhancing body volume parts control in the particles reiforced metal-base composition about pressure casting process is very few, the low volume parts of pressure casting process preparation, and small size SiC particle enhanced aluminum-based composite material does not appear in the newspapers as yet.

Summary of the invention: the present invention is intended to by add the aluminum matrix alloy powder in prefabricated section, reduce and strengthen the volume parts that the body particle accounts in the whole prefabricated section, finally by the low volume parts SiCp/Al matrix material of pressure die casting method preparation, solve pressure casting process and prepare small size SiC particle enhanced aluminum-based composite material volume parts height, the problem of plasticity difference, the preparation process of controlled volume umber SiCp/Al matrix material is: the first step is the preparation mixed powder: SiC particle and aluminium powder are mixed than relation according to following weight: when needing the SiC particle to account for prepared SiCp/Al total composite volume 15～25%, according to

$\frac{a/{\mathrm{\ρ}}_{\mathrm{SiC}}}{b/{\mathrm{\ρ}}_{\mathrm{Al}}}=\frac{x}{(44+\frac{3(x-15)}{10})-x}$

Formula calculates the weight ratio that needs to add SiC particle and aluminium powder, and a, b are respectively the weight of SiC particle and aluminium powder in the formula, and x is a bit in 15～25%, ρ _SicAnd ρ _AlBe respectively the density of SiC particle and aluminium powder; When needing the SiC particle to account for prepared SiCp/AI total composite volume 25～45%, according to

$\frac{a/{\mathrm{\ρ}}_{\mathrm{SiC}}}{b/{\mathrm{\ρ}}_{\mathrm{Al}}}=\frac{x}{(47+\frac{2(x-25)}{20})-x}$

Formula calculates the weight ratio that needs to add SiC particle and aluminium powder, and a, b are respectively the weight of SiC particle and aluminium powder in the formula, and x is a bit in 25～45%, ρ _SicAnd ρ _AlBe respectively the density of SiC particle and aluminium powder, aforementioned SiC particulate granularity is 0.1 μ m～1mm; Second step was the preparation prefabricated section: the composite grain and the dehydrated alcohol that prepare are mixed with slurry by weight 1: 2～4, mechanically mixing 10～40 hours is poured filtering particle in the prefabricated section mould into, removes dehydrated alcohol, when dehydrated alcohol is can't see on prefabricated section mould top, put into pressure head, slowly be forced into 0.5～5Mpa, pressurize 2～10 minutes, move back mould then, naturally shady doing one day dried 1～10 hour under 80～160 ℃ of temperature at last, promptly got prefabricated section; The 3rd step was pressure die casting: prefabricated section is put into die casting be preheated to 400～550 ℃, aluminium is heated to 800 ℃ makes it whole fusings, aluminium liquid after will melting is then poured in the die casting, the pressure that adds for the first time 5～10Mpa, add for the second time the pressure of 100～200Mpa, pressurize promptly got the SiCp/Al matrix material in 1～10 minute." SiCp/Al matrix material " i.e. " enhancing aluminum-base composite material by silicon carbide particles " in the present specification, the present invention is applicable to that pressure casting process prepares 0.1 μ m～1mmSiC particle-reinforced aluminum and alloy composite materials thereof.Result of study shows, adopts the present invention to expand to 15～50% by original 40～50% with strengthening body volume parts controlled range in the small size SiC particle enhanced aluminum-based composite material.Low volume parts (less than 30%) the SiCp/Al matrix material of the present invention's preparation, in the time of 300 ℃, extrusion ratio can reach 36: 1 above, room temperature tensile unit elongation to be brought up to more than 3%, and 25% the 3.5 μ mSiCp/Al performance of composites indexs of utilizing that the present invention prepares are as follows: 1, density: as cast condition 98.6%; Extruding attitude 99.1%; 2, hardness: as cast condition 91Hv; Extruding attitude 93Hv; 3, stretch percentage elongation: as cast condition 3.3%; Extruding attitude 5.7%; 4, breakdown point: as cast condition 140～160Mpa; Extruding attitude 230～250Mpa; 5, plasticity-: extrusion ratio was greater than 36: 1.

Embodiment one: the present embodiment preparation process is: the first step is the preparation mixed powder: test-results shows, mixing prefabricated section for the pure aluminium powder of mean sizes 3.5 μ MSiC particles and 10 μ m, when under 2Mpa pressure, preparing prefabricated section, the SiC particle accounts for 15 of whole prefabricated section volume～25% o'clock, and the volume parts of prefabricated section is 44～47%; The SiC particle accounts for 25 of whole prefabricated section volume～45% o'clock, the porosity of prefabricated section is 47～49%, can be similar in these two intervals that to think that the SiC particle accounts for the volume parts of the volume parts of whole prefabricated section and composite grain linear, when needing the SiC particle to account for prepared SiCp/Al total composite volume 15～25%, according to

$\frac{a/{\mathrm{\ρ}}_{\mathrm{SiC}}}{b/{\mathrm{\ρ}}_{\mathrm{Al}}}=\frac{x}{(44+\frac{3(x-15)}{10})-x}$

Formula calculate to need adds the weight ratio of SiC particle and aluminium powder, and a, b are respectively the weight of SiC particle and aluminium powder in the formula, and x is in 15～25%～some ρ _SiCAnd ρ _AlBe respectively the density of SiC particle and aluminium powder; When needing the SiC particle to account for prepared SiCp/Al total composite volume 25～45%, according to

$\frac{a/{\mathrm{\ρ}}_{\mathrm{SiC}}}{b/{\mathrm{\ρ}}_{\mathrm{Al}}}=\frac{x}{(47+\frac{2(x-25)}{20})-x}$

Formula calculates the weight ratio that needs to add SiC particle and aluminium powder, and a, b are respectively the weight of SiC particle and aluminium powder in the formula, and x is a bit in 25～45%, ρ _SiCAnd ρ _AlBe respectively the density of SiC particle and aluminium powder; Second step was the preparation prefabricated section: the composite grain and the dehydrated alcohol that prepare are mixed with slurry by weight 1: 2～4, mechanically mixing 10～40 hours is poured filtering particle in the prefabricated section mould into, removes dehydrated alcohol, when dehydrated alcohol is can't see on prefabricated section mould top, put into pressure head, slowly be forced into 0.5～5Mpa, pressurize 2～10 minutes, move back mould then, naturally shady doing one day dried 1～10 hour under 80～160 ℃ of temperature at last, promptly got prefabricated section; The 3rd step was pressure die casting: prefabricated section is put into die casting be preheated to 400～550 ℃, aluminium is heated to 800C makes it whole fusings, aluminium liquid after will melting is then poured in the die casting, the pressure that adds for the first time 5～10Mpa, add for the second time the pressure of 100～200Mpa, pressurize promptly got the SiCp/Al matrix material in 1～10 minute.

Embodiment two: the composite grain and the dehydrated alcohol that prepare were mixed with slurry by weight 1: 2, mechanically mixing 20 hours, pour filtering particle in the prefabricated section mould into, remove dehydrated alcohol, when dehydrated alcohol is can't see on prefabricated section mould top, put into pressure head, slowly be forced into 2Mpa, pressurize 5 minutes, further remove the dehydrated alcohol in the prefabricated section, move back film then, shady naturally doing one day dried 4 hours under 120 ℃ of temperature at last, removal is adsorbed on the ethanol of particle surface, use in order to pressure die casting, promptly get prefabricated section, the prefabricated section size is preferably below Φ 55 * 60mm; The 3rd step was pressure die casting: secondary pressure method-low-pressure permeability is adopted in pressure die casting, high pressure pressurize cooling.Prefabricated section is put into die casting be preheated to 400～550 ℃, aluminium is heated to 800 ℃ makes it whole fusings, aluminium liquid after will melting is then poured in the die casting, the infiltration pressure of pressurization is 5～10Mpa for the first time, secondary pressurization refrigerative pressure is 100～200Mpa, pressurize 5 minutes promptly gets the SiCp/Al matrix material.

Embodiment three: the different SiC particle and the weight ratio of aluminium powder in the mixed powder, different preheating temperatures and first and second different pressure, the invention effect is different, embodiment sees the following form:

Sequence number	The weight ratio of SiC particle and aluminium powder in the mixed powder	Preheating temperature (℃)	Pressure (MPa)		The invention effect
									A pressure	Secondary pressure	Depth of penetration (mm)	The SiC volume fraction	Density (%)	Stretch percentage elongation (%)
			1	0.36	400	5	150	30							15	93	2.8
2	0.61	400							5	150	50	15.5	97.5	3.5
			3	0.93	400	5	150	All infiltrations							20.3	98	3.3
4	1.35	400							5	150	All infiltrations	25.2	98.2	3.2
			5	0.36	450	5	150	25							19	92	1.5
6	0.61	450							5	150	52	15.4	97.7	3.7
			7	0.93	450	5	150	All infiltrations							20.2	98.4	3.5
8	1.35	450							5	150	All infiltrations	25.1	98.5	33
			9	0.36	550	5	150	10							23	90.8	3.5
10	0.61	550							5	150	50	16.3	97.3	3.5
			11	0.93	550	5	150	All infiltrations							2.9	98.3	3.4
12	1.35	550							5	150	All infiltrations	25.4	98.6	3.3
			13	0.36	500	10	150	14							21	90.5	3.5
14	0.61	500							10	150	45	16.5	96.9	3.4
			15	0.93	500	10	150	All infiltrations							21	97.6	3.3
16	1.35	500							10	150	All infiltrations	25.6	98.1	3.2
			17	2.03	500	5	150	All infiltrations							30.2	97.8	2.8
18	3.19	500							5	150	All infiltrations	35.1	99	2.2
			19	5.58	500	5	150	All infiltrations							40	9.2	1.5
20	13.33	500							5	150	All infiltrations	45	99.2	1.1

Claims (1)

1, a kind of pressure die casting preparation method of controlled volume umber SiCp/Al matrix material, the preparation process that it is characterized in that it is: the first step is the preparation mixed powder: SiC particle and aluminium powder are mixed than relation according to following weight: when needing the SiC particle to account for prepared SiCp/Al total composite volume 15～25%, according to

$\frac{a/{\mathrm{\ρ}}_{\mathrm{SiC}}}{b/{\mathrm{\ρ}}_{\mathrm{Al}}}=\frac{x}{(44+\frac{3(x-15)}{10})-x}$

Formula calculates the weight ratio that needs to add SiC particle and aluminium powder, and a, b are respectively the weight of SiC particle and aluminium powder in the formula, and x is a bit in 15～25%, ρ _SicAnd ρ _AlBe respectively the density of SiC particle and aluminium powder; When needing the SiC particle to account for prepared SiCp/AI total composite volume 25～45%, according to

$\frac{a/{\mathrm{\ρ}}_{\mathrm{SiC}}}{b/{\mathrm{\ρ}}_{\mathrm{Al}}}=\frac{x}{(47+\frac{2(x-25)}{20})-x}$

Formula calculates the weight ratio that needs to add SiC particle and aluminium powder, and a, b are respectively the weight of SiC particle and aluminium powder in the formula, and x is a bit in 25～45%, ρ _SicAnd ρ _AlBe respectively the density of SiC particle and aluminium powder, aforementioned SiC particulate granularity is 0.1 μ m～1mm; Second step was the preparation prefabricated section: the composite grain and the dehydrated alcohol that prepare are mixed with slurry by weight 1: 2～4, mechanically mixing 10～40 hours is poured filtering particle in the prefabricated section mould into, removes dehydrated alcohol, when dehydrated alcohol is can't see on prefabricated section mould top, put into pressure head, slowly be forced into 0.5～5Mpa, pressurize 2～10 minutes, move back mould then, naturally shady doing one day dried 1～10 hour under 80～160 ℃ of temperature at last, promptly got prefabricated section; The 3rd step was pressure die casting: prefabricated section is put into die casting be preheated to 400～550 ℃, aluminium is heated to 800 ℃ makes it whole fusings, aluminium liquid after will melting is then poured in the die casting, the pressure that adds for the first time 5～10Mpa, add for the second time the pressure of 100～200Mpa, pressurize promptly got the SiCp/Al matrix material in 1～10 minute.