WO2013167448A1

WO2013167448A1 - Use of a complex metal alloy containing aluminum for stereolithography

Info

Publication number: WO2013167448A1
Application number: PCT/EP2013/059095
Authority: WO
Inventors: Samuel Kenzari; Adnene SAKLY; David Bonina; Serge Corbel; Vincent Fournee
Original assignee: Universite De Lorraine; Centre National De La Recherche Scientifique (Cnrs)
Priority date: 2012-05-11
Filing date: 2013-05-02
Publication date: 2013-11-14
Also published as: FR2990375B1; FR2990375A1

Abstract

The invention relates to the use of a mixture of a photopolymerisable resin and a complex metal alloy containing aluminum in a method for stereolithography by photopolymerisation or three-dimensional printing by photopolymerisation. The invention also relates to a method for producing a three-dimensional part by stereolithography by photopolymerisation, said method comprising a step of solidifying said three-dimensional part, layer by layer, in a liquid medium comprising a mixture of a photopolymerisable resin and a complex metal alloy containing aluminum, by exposing said liquid medium to ultraviolet radiation. The invention further relates to a three-dimensional part produced by said method.

Description

USE OF A COMPLEX ALUMINUM METAL ALLOY FOR STEREOLITHOGRAPHY

Technical area

The present invention relates to the use of a blend of a photopolymerizable resin and an aluminum complex metal alloy in a photopolymerization stereolithography process or three-dimensional photopolymerization printing.

It also relates to a process for producing a three-dimensional part by stereolithography by photopolymerization, said method comprising a step of solidification, layer by layer, of said three-dimensional part in a liquid medium comprising a mixture of a resin photopolymerizable and complex aluminum alloy metal alloy, by exposing said liquid medium to ultraviolet radiation, and a three-dimensional piece obtained by this method.

The present invention finds applications particularly in the field of prototyping.

In the description below, references in brackets ([]) refer to the list of references at the end of the examples.

State of the art

Rapid prototyping involves the physical fabrication of a three-dimensional object from computer modeling. This field is in full expansion and seeks to standardize three-dimensional printing currently not very accessible due to the costs of rapid prototyping devices.

Stereolithography is a rapid prototyping process, born in the 1980s, that consists of making an object in three dimensions by superposition of polymer layers, usually epoxy resins.

The fabrication of three-dimensional objects by stereolithography is performed layer by layer about 100 microns thick by scanning a focused ultraviolet laser beam at the surface of a liquid resin bath. The trajectory of the beam corresponding to the geometric pattern of each of the layers is controlled by software describing the geometry of the objects to be produced.

Conventional methods of stereolithography are presented in particular in US Pat. No. 4,575,330 [1].

Objects made from current resins are very fragile. In particular, objects currently manufactured by stereolithography have a very low resistance to wear and friction, making the stereolithography processes unattractive.

Composite resins, reinforced with ceramic particles or colloidal silica, have been developed to improve the mechanical properties of the objects produced. However, the excessive cost of these composite resins is not compatible with commercial exploitation.

There is currently no composite resin for stereolithography for low-cost production of three-dimensional objects having satisfactory friction and wear resistance.

There is therefore a real need to develop composite resins overcoming these defects, disadvantages and obstacles of the prior art, in particular to reduce the cost of producing objects in three dimensions by stereolithography, while improving the mechanical strength of these objects. .

Presentation of the invention

The present invention precisely meets this need of the prior art by providing means to reduce production costs three-dimensional objects by stereolithography or by three-dimensional printing by photopolymerization, while improving the mechanical properties of the objects produced.

Surprisingly, the inventors have discovered that complex aluminum alloys, when mixed with a photopolymerizable resin, can stereolithographically produce three-dimensional parts with remarkable mechanical characteristics. Indeed, up to now, the use of conventional aluminum alloys normally makes it impossible to construct a composite part based on resin matrix and aluminum particles in three dimensions by stereolithography or by three-dimensional printing. by photopolymerization, because the penetration depth of the ultraviolet radiation in the photopolymerizable liquid resin is greatly limited by the presence of the aluminum particles. Tests have shown that it is impossible to obtain a three-dimensional object by stereolithography containing aluminum particles at levels similar to that of the complex aluminum-based metal alloys used herein.

Thus, the present invention particularly relates to the use of a mixture of a photopolymerizable resin and an aluminum-based complex metal alloy in a stereolithography process by photopolymerization or by three-dimensional printing by photopolymerization.

As used herein, "photopolymerization stereolithography method" means any stereolithography process as well as any three-dimensional printing process using ultraviolet radiation. In other words, it is any layer-by-layer production process of a three-dimensional object, in particular from a photopolymerizable resin. This may be for example a three-dimensional printing process by light-curing, for example a Multiple jet patterning (MJM) printing method or UV printing method of liquid resin layer.

Preferably, the aluminum complex metal alloy comprises an atomic percentage of aluminum greater than 50%.

According to the invention, the complex metal alloy based on aluminum can be defined as a quasi-crystalline aluminum alloy.

As used herein, the term "quasi-crystalline alloy" means an alloy which comprises one or more quasi-crystalline phases which are either quasi-crystalline phases in the strict sense or approximate phases. The quasicrystalline phases in the strict sense are phases exhibiting symmetries of rotation normally incompatible with translational symmetry, that is to say axis of rotation symmetries of order 5, 8, 10 or 12, these symmetries being revealed by diffraction techniques. By way of example, mention may be made of the icosahedral moment group phase m3 5 and the phase group decagonal phase 10 / mmm.

The approximative phases or approximate compounds are true crystals insofar as their crystallographic structure remains compatible with translational symmetry, but which exhibit, in the electron diffraction pattern, diffraction patterns whose symmetry is close to one another. symmetry of order 5, 8, 10 or 12. These are phases characterized by an elementary cell containing several tens, or even hundreds of atoms, and whose local order presents arrangements of almost icosahedral or decagonal symmetry similar to the phases quasi-crystalline parents.

Among these phases, there may be mentioned, by way of example, the orthorhombic phase Oi, characteristic of an alloy having the atomic composition AI ₆ 5Cu ₂ OFeioCr ₅ , whose mesh parameters in nm are: ao ⁽¹⁾ = 2.366, b ₀ ⁽¹⁾ = 1, 267, c ₀ ⁽¹⁾ = 3,252. This orthorhombic phase d is said to approximate the decagonal phase. The nature of the two phases can be identified by transmission electron microscopy. We can also mention the rhombohedral phase of parameters aR = 3.208 nm, a = 36 °, present in the alloys of atomic composition close to Al ₆₄ Cu 2 ₄ Fei 2. This phase is an approximate phase of the icosahedral phase.

Orthorhombic O 2 and O 3 phases of respective parameters may also be mentioned in nm ao ⁽²⁾ = 3.83; bo ⁽²⁾ = 0.41; Co ⁽²⁾ = 5.26 as well as ₀ ⁽³⁾ = 3.25; b ₀ ⁽³⁾ = 0.41; c ₀ ⁽³⁾ = 9.8, present in an alloy of atomic composition AI ₆ 3Cui ₇ , 5Coi ₇ , 5Si2 or the orthorhombic phase O ₄ of parameters in nm ao ⁽⁴⁾ = 1, 46; Bo ⁽⁴⁾ = 1.23; Co ⁽⁴⁾ = 1, 24, which is formed in the alloy whose atomic composition is

We can also mention a phase C, of cubic structure, very often observed in coexistence with the approximate or quasi-crystalline phases true. This phase, which is formed in certain Al-Cu-Fe and Al-Cu-Fe-Cr alloys, consists of a substructure, by the chemical effect of the alloying elements with respect to the aluminum sites, of a phase structure-type CI-Cs and lattice parameter a _<\ = 0.297 nm. A diffraction pattern of this cubic phase has been published for a pure cubic phase sample and atomic composition AI ₆₅ Cu2oFei ₅ in number of atoms.

We can also mention a phase H of hexagonal structure which derives directly from the phase C as demonstrated by the epitaxial relationships observed by electron microscopy between crystals of the C and H phases and the simple relations that link the parameters of the crystal lattices, namely aH = 3 / 2α _1/3 (4.5% grass) and cH = 3 / 2α _{January 12}

(at 2.5% near). This phase is isotype of a hexagonal phase, noted ΦΑΙΜη, found in Al-Mn alloys containing 40% by weight of Mn.

The cubic phase, its superstructures and the phases derived from them constitute a class of approximate phases of the quasi-crystalline phases of neighboring compositions. The quasi-crystalline alloys of the Al-Cu-Fe system and the Al-Fe-Co-Cr system are particularly suitable for the implementation of the present invention.

Preferably, according to the invention, the aluminum-based complex metal alloy is chosen from the group comprising Al _{6 2} Cu 25.5 Fe ₂ 2.5, Al _{5 9} Cu 25.5 Fe ₂ _2.5 B ₃ , Al ₂ Cl ₂ Fe ₂ Cr ₂ O and Al _7. , Fe ₃ ₈ iCoi2,8Cr _7, 8. These complex alloys have the advantage of having tribological properties (friction and wear), surface (low surface energy), mechanical properties (hardness, yield strength and Young's modulus), thermal conductivity and electrical properties (high resistivity). , different from those of crystalline aluminum alloys.

These alloys are marketed by Saint-Gobain. In particular, the alloy AI ₅ 9Cu2 _5.5 Fei2, ₄ B3 is sold under the name Cristome F1, the alloy AI iCu9 _7, ₇ Fe8,7Cri _0, 6 is marketed under the name Cristome A1, and the alloy AI ₇ i, ₃ Fe 8, iCo 2, 8Cr ₇ , ₈ is sold under the name Cristome BT1.

The volume fraction of complex metal alloy in the mixture may be between 5 and 50% (ie between 15 and 65% by weight of the total mixture), for example between 5 and 30%. Preferably, the volume fraction of complex metal alloy is between 10 and 20% of the mixture.

The particle size of the complex metal alloy may be between 1 and 50 μιτι. Preferably, it is between 1 and 30 μιτι, more preferably between 1 and 20 μιτι.

According to the invention, any photopolymerizable resin suitable for stereolithography can be used. For example, the photopolymerizable resin may be selected from the group consisting of acrylate compounds, urethane acrylate compounds, epoxy compounds, epoxy acrylate compounds, vinyl ether compounds and a mixture of these compounds. Preferably, the photopolymerizable resin is selected from available resins such as: Accura® 60, Accura® 55, Accura® 25 from 3D Systems.

The volume fraction of photopolymerizable resin in the mixture may be between 50 and 95% (ie between 35 and 85% by weight of the total mixture), for example between 70 to 95%. Preferably, the volume fraction of photopolymerizable resin is between 80 and 90% of the mixture.

According to the present invention, the mixture of a photopolymerizable resin and an aluminum complex metal alloy may comprise a polymerization initiator.

As an example of a polymerization initiator, there may be mentioned a commercial thermo-initiator such as azobisisobutyronitrile (AIBN). When polymerization initiators are added to the mixture, they may be added at a concentration of between 0.75 and 2% by weight of the mixture.

The components of the mixture may be mixed by any suitable mixing means known to those skilled in the art. For example, the mixing means may be chosen from the group comprising a mixer (paint type) or a planetary mill. Preferably, the mixing means is a planetary mill, with a ratio of total mixture weight / bead weight of 2/1.

As used herein, "blend components" means the components of the blend of a photopolymerizable resin and an aluminum complex metal alloy. It is at least the photopolymerizable resin and the complex metal alloy based on aluminum as defined in the present invention. It may also be, if it is present, the polymerization initiator.

Advantageously, according to the invention, the components of the mixture are mixed homogeneously. This advantageously makes it possible to obtain parts having homogeneous mechanical properties. The present invention also relates to a method for producing a three-dimensional part by stereolithography by photopolymerization, said method comprising a step of solidification, layer by layer, of said three-dimensional part in a liquid medium comprising a mixture of a photopolymerizable resin and a complex metal alloy based on aluminum, by exposing said liquid medium to ultraviolet radiation.

The aluminum complex metal alloy and the photopolymerizable resin are as defined in the present invention.

The method for producing a three-dimensional piece by stereolithography by photopolymerization according to the present invention can be implemented by any stereolithography device known to those skilled in the art. It may be for example a device branded 3D Systems under the trade name SLA 250 or iPro 8000 SLA.

The stereolithography device can be controlled by any appropriate software. This may be for example the 3D Systems control software.

The skilled person is able to implement the method of the present invention. Indeed, the general principle of stereolithography is well known to those skilled in the art [1].

The present invention also relates to a method for producing a three-dimensional part by three-dimensional printing by photopolymerization, said method comprising a step of solidification, layer by layer, of said three-dimensional part by successive steps of:

a) depositing a liquid medium comprising a mixture of a photopolymerizable resin and an aluminum complex metal alloy on a support, and b) exposing said liquid medium to ultraviolet radiation. The aluminum complex metal alloy and the photopolymerizable resin are as defined in the present invention.

The method for producing a three-dimensional part by three-dimensional printing by light-curing according to the present invention can be carried out by any three-dimensional printing device known to those skilled in the art. It may be for example a 3D Systems brand device under the trade name 3-D In Vision.

In the process of producing a three-dimensional piece by three-dimensional photopolymerization printing according to the present invention, the carrier may be any suitable carrier for three-dimensional printing by photopolymerization. These supports are well known to those skilled in the art. It may be for example a wax support which has the advantage of being removable by heat treatment. Those skilled in the art understand that the support of the layers may also correspond to a layer that has been previously produced during the process.

According to the invention, the thickness of the layers produced during the solidification step may be between 20 and 120 μιτι, for example between 25 and 100 μιτι. Preferably, the thickness of the layers produced during the solidification step is between 40 and 80 μιτι.

The skilled person is able to set the ultraviolet radiation. Typically, the wavelength of ultraviolet radiation is between 300 and 450 nm, preferably 355 nm. The scanning speed of the ultraviolet radiation may be between 0.01 and 0.5 m / s, preferably 0.04 m / s. The power of ultraviolet radiation can be between 100 mW (milliwatt) and 1 W, preferably 140 mW. As an example of ultraviolet radiation adapted to the implementation of the method of the present invention, it is possible to mention the laser diode pumped Nd: YAG UV laser via an optical fiber (Model J40-X15SC-355Q-2, Spectra-Physics).

Typically, the stereolithography device implemented in the present invention comprises a thermostatable tray. This thermostatable tray makes it possible to maintain the mixture of a photopolymerizable resin and a complex metal alloy based on aluminum at a predetermined temperature. For carrying out the process of the present invention, the thermostable tray holds the mixture of a photopolymerizable resin and an aluminum complex metal alloy in a liquid form. Advantageously, the temperature of the mixture is maintained at a temperature between 20 and 30 ° C, preferably at a temperature of 27 ° C.

The present invention also relates to a three-dimensional part obtained by any of the methods of the present invention.

These parts have surprising mechanical characteristics thanks to the use of the mixture of the photopolymerizable resin and the complex metal alloy based on aluminum according to the invention.

The present invention makes it possible in particular, with comparable mechanical properties, to reduce material costs for the manufacture of composite parts by stereolithography of the order of 30%.

In addition, the present invention makes it possible to obtain functional parts having a better resistance to friction (approximately 30%) and to wear (approximately 50%) in comparison with the composite parts currently manufactured by stereolithography.

Other advantages may still appear to those skilled in the art on reading the examples below, illustrated by the attached figure, given for illustrative and non-limiting. Brief description of the figures

FIG. 1 represents a diagram of a stereolithography device (A) at the beginning and (B) during a process for producing a three-dimensional part. In this figure, "M" represents the galvanometric mirrors, "SFD" represents the dynamic focusing system, "UV" represents the source of ultraviolet radiation, "G" represents the support grid, "B" represents a thermostable tank, "RI Represents the liquid resin, "Rs" represents the solid resin forming a three-dimensional part, "S" represents the motorized support allowing to adjust the height of the support grid in the thermostatable tray, and "Z" represents the displacement of the support grid along the motorized support "S".

EXAMPLES

Example 1 Preparation of a composite mixture

A composite blend comprising a mixture of a photosensitive resin powder and an aluminum complex metal alloy (CMA) powder was prepared.

The photoresist used was an "Accura" resin marketed by the company 3D Systems. This resin is referred to as "SLA" in the examples.

In the examples, "CMA" is a quasi-crystalline alloy AlCuFeB nominal atomic composition AI ₅ 9Cu2 _5.5 Fei2,5B3 sold under the name Cristome F1 by Saint-Gobain, whose size is between 1 and 25 μιτι . This alloy consists of the phase of complex structure (icosahedral i) isostructural at phase i-AI ₆ 2Cu25.5Fei2.5 and a cubic isostructural phase at the phase -AI ₅ o (CuFe) ₅ o-

Each grade of material was accurately weighed so as to obtain a mixture of 50% by weight of resin and 50% by weight of CMA. The resin and the CMA were mixed homogeneously using a planetary mill marketed by the company Fritsch, model Pulverisette 5. This allowed, after photopolymerization in accordance with Example 2 below, to obtain three-dimensional parts with homogeneous mechanical properties.

Example 2: Manufacture of three-dimensional objects (3D) made of composite material

A 3D object was prepared by UV irradiating a liquid medium prepared from the composite mixture shown in Example 1.

For this, 500 grams of CMA powders were poured into 440 ml (milliliters) of SLA resin. The liquid medium obtained was mixed using a planetary mill and then poured into a tank thermostated at 27 ° C.

The stereolithography device used was a 3D Systems trademark device under the trade name SLA 250 or iPro 8000 SLA. A diagram of the device during its implementation is shown in Figure 1.

This device comprises in particular galvanometric mirrors

("M"), a dynamic focusing system ("SFD") focusing the UV radiation, a motorized support grid ("G") integrated in a thermostable tray ("B") and a scraper (not shown in FIG. ). The device was computer controlled by the OPTOFORM (3D Systems) control software.

The UV radiation used was a laser diode pumped Nd: YAG UV laser via an optical fiber (Model J40-X15SC-355Q-2, Spectra-Physics). The wavelength was close to 355 nm. The scanning speed of the laser beam was 0.04 m / s and its power was 140 mW. The three-dimensional object was manufactured point by point by superposition of layers having a thickness of 50 μΜ, by scanning the laser beam. The trajectory of the laser beam, corresponding to the geometric pattern of a determined layer, was controlled by the software describing the geometry of the corresponding layer of the piece modeled in the software.

The first layer was made on the surface of the support grid ("G") when it was positioned just below the surface of the liquid medium ("RI", comprising the photopolymerizable resin and the CMA). Once the first layer was made, the support grid ("G") was lowered using the motorized support ("S") to make a second layer. The operation was repeated until the complete production of the three-dimensional object, modeled in the software. Example 3: Properties of the obtained parts

3.1 Coefficient of friction

The friction properties were measured using a micro tribometer of the pion / disc type marketed by CSM Instruments. The wiper used was a steel ball (100Cr6) with a diameter of 6 mm. The normal load on the wiper was 5 N. The friction movement was circular with a radius of 5 mm. The tests were carried out without lubrication, at atmospheric pressure and at 20 ° C. The relative humidity was between 40 and 50%.

Prior to the friction test, the surface of the samples was water-polished with SiC abrasive paper up to grade 4000. Then, the samples were ethanol-blotted and electric-kiln dried. Sample and ball surfaces were cleaned with acetone just prior to testing.

The rotational speed was 150 rpm. The ratio of the lateral force to the normal force defines the coefficient of friction μ. The coefficient of friction of the three-dimensional objects obtained from the photopolymerizable resin / CMA mixture of Example 1 was compared, under the same experimental conditions, with three-dimensional objects obtained from photopolymerizable resin alone or from a resin reinforced by a ceramic (Bluestone marketed by 3D Systems).

The coefficient of friction measured using the tribometer shows a gain of about 30% for the mixture prepared in Example 1 compared to the resin alone or reinforced by a ceramic (Bluestone 3D Systems)

In addition, the results obtained show that the wiper (steel ball 100Cr6) is not worn by the three-dimensional objects obtained from the mixture of Example 1 or the resin alone, while it is very heavily used by three-dimensional objects obtained from the Bleustone resin.

3.2 Wear tests

The wear tests were carried out using an automatic polisher marketed by Struers.

The principle of the test is as follows: a 25 mm diameter cylindrical sample is placed in a standard rotating sample holder which is itself placed on a polishing disc (SiC 500, Struers). The polishing plate is driven with a speed of rotation of 150 rpm while the sample holder rotates at the same speed. The wear is translated by the difference in volume of the sample after the test.

The wear of the samples obtained from the photopolymerizable resin / CMA mixture of Example 1 was compared, under the same experimental conditions, with samples obtained from photopolymerizable resin alone. Samples obtained from photopolymerizable resin alone have 40% wear volume additional to the samples obtained from the mixture of Example 1.

In the case of a comparison with the Bleustone resin, the wear volume is similar to the samples obtained from the photopolymerizable resin / CMA mixture of Example 1.

3.3 Apparent density.

Bulk density was measured by the volume difference method before / after each wear test.

The three-dimensional objects obtained from the photopolymerizable resin / CMA mixture of Example 1 have a bulk density measured by the mass / volume ratio of the piece which is close to 99% of the theoretical density.

3.4 Shore hardness P.

Shore D hardness was measured according to the standard method ASTM D2240.

The three-dimensional objects obtained from the photopolymerizable resin / CMA mixture of Example 1 have an average Shore D hardness of 88 + 1 in comparison with that of the three-dimensional objects obtained from the resin alone (84 + 1) .

List of references

[1] US 4,575,330

Claims

1. Use of a mixture of a photopolymerizable resin and an aluminum complex metal alloy in a photopolymerization stereolithography process or three-dimensional photopolymerization printing.

The use of claim 1, wherein the aluminum complex metal alloy comprises an atomic percentage of aluminum greater than 50%.

3. Use according to claim 1 or 2, wherein the complex aluminum alloy metal is selected from the group consisting of AI ₆ 2Cu ₂ 5,5Fei ₂ , 5, AI ₅ 9Cu25,5Fei2,5B ₃ , A CugjFesjCrio and Al7i, ₃ Fe8, iCo2.8Cr ₇ , 8.

Use according to any one of claims 1 to 3, wherein the photopolymerizable resin is selected from the group consisting of acrylate compounds, urethane acrylate compounds, epoxy compounds, epoxy acrylate compounds, vinyl ether compounds and mixture of these compounds.

5. Use according to any one of claims 1 to 4, wherein the volume fraction of photopolymerizable resin in the mixture is between 50 and 95% and the volume fraction of complex metal alloy in the mixture is between 5 and 50 %.

Use according to any one of claims 1 to 5, wherein the mixture of a photopolymerizable resin and an aluminum complex metal alloy further comprises a polymerization initiator.

A process for producing a three-dimensional part by photopolymerization stereolithography, said method comprising a layer-by-layer solidification step of said three-dimensional part in a liquid medium comprising a mixture of a photopolymerizable resin and a a complex metal alloy based on aluminum, by exposing said liquid medium to ultraviolet radiation.

A process for producing a three-dimensional part by three-dimensional printing by photopolymerization, said method comprising a layer-by-layer solidification step of said three-dimensional part by successive steps of:

a) depositing a liquid medium comprising a mixture of a photopolymerizable resin and an aluminum complex metal alloy on a support, and b) exposing said liquid medium to ultraviolet radiation.

The process of claim 7 or 8, wherein the aluminum complex metal alloy is as defined in claim 2 or 3.

The process according to claim 7 to 9, wherein the photopolymerizable resin is as defined in claim 4.

1 1. Three-dimensional part obtained by the process according to any of claims 7 to 10.