Patent Description:
Various additive manufacturing processes are known in the art for forming one or more parts. The term "additive manufacturing" may describe a process where a part or parts are formed by accumulating and/or fusing material together, typically in a layer-on-layer manner. Layers of material, for example, may be cold sprayed sequentially onto one another to form the part(s). In another example, layers of material may be sintered or otherwise melted sequentially onto one another to form the part(s).

Part(s) are typically additively manufactured from metal powder. This metal powder may be degassed in order to remove entrained gasses and/or moisture therefrom, which if not removed can create various defects within the part(s). However, if the degassed metal powder is exposed to air or atmosphere containing residual moisture during storage and/or loading into an additive manufacturing system, the degassed metal powder may re-adsorb moisture. The metal powder therefore may require additional degassing, which can increase manufacturing time and cost.

<CIT>, <CIT> and <CIT> all disclose additive manufacturing systems of the prior art.

<CIT> discloses coated powder particles for producing three-dimensional bodies by means of a layer constituting method.

There is a need in the art for improved additive manufacturing materials and processes.

According to an aspect of the invention, a process is provided for forming a part using an additive manufacturing system, as claimed in claim <NUM>.

The metal powder core of at least one of the particles may be a degassed metal powder core.

The coating of at least one of the particles may be adapted to prevent the core from adsorbing moisture.

The core of at least one of the particles may include a single metal particle. In addition or alternatively, the core of at least one of the particles may include a plurality of metal particles.

The core of at least one of the particles may be configured from or otherwise include at least one of the following materials: aluminum, copper, titanium, nickel and steel.

The coating of at least some of the particles may be removed to expose the cores of the respective particles. The coating may be removed through decomposition and/or volatization.

Material is described below for additively manufacturing one or more parts. This additive manufacturing material includes a plurality of discrete particles that collectively form powder. An exemplary of one of these additive manufacturing particles <NUM> is illustrated in <FIG> and described below. It is worth noting, however, that one or more of the additive manufacturing particles included in the additive manufacturing material may alternatively have different configurations and/or compositions than that described below and illustrated in <FIG>.

The additive manufacturing particle <NUM> of <FIG> includes a metal powder core <NUM> covered and/or encapsulated by a coating <NUM>. The core <NUM> may include one or more metal particles. Each of these metal particles may be composed from one or more of the following core materials: aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), steel, and/or alloys thereof. One or more of the metal particles, of course, may also or alternatively be composed from one or more core materials other than those described above.

The core <NUM> may be a degassed metal powder core. For example, before being encapsulated within the coating <NUM>, the core <NUM> may be degassed to remove entrained gas, adsorbates and/or moisture therefrom. Various degassing processes are known in the art and therefore are not described in further detail.

The core <NUM> may have a size (e.g., an average diameter) of between about five micrometers (<NUM>) and about five-hundred micrometers (<NUM>); e.g., between about twenty micrometers (<NUM>) and about sixty micrometers (<NUM>). The present invention, however, is not limited to the foregoing exemplary core sizes.

The coating <NUM> is adapted to substantially reduce or prevent the core <NUM> from adsorbing moisture. The coating <NUM> therefore may enable the additive manufacturing particle <NUM> to be stored outside of a controlled additive manufacturing environment (e.g., a vacuum or noble gas environment) without compromising the core material for subsequent additive manufacturing. In contrast, a metal particle without such a coating may adsorb moisture during the storage and/or transportation thereof. This moisture may subsequently cause surface defects and/or porosity defects in a part formed from the now non-degassed metal particle.

Referring again to <FIG>, the coating <NUM> may also be adapted to partially or substantially completely decompose and/or volatize in order to partially or substantially completely expose the core <NUM> for subsequent additive manufacturing. In this manner, the coating <NUM> may be removed from the core <NUM> prior to formation of the part(s), which reduces the likelihood of or substantially prevents the coating material from altering the mechanical properties and/or the intended chemical composition of the part(s).

The coating <NUM> is a non-metal coating comprising a polymer-ceramic coating. The coating <NUM>, for example, may be composed from one or more of the coating materials listed below in Table I that meet this definition.

The coating material may be deposited on the core <NUM> to form the coating <NUM> through one or more of the following processes: chemical adsorption, physical adsorption and/or covalent bonding. Various chemical adsorption, physical adsorption and covalent bonding processes are known in the art and therefore are not described in further detail. The coating material, of course, may also or alternatively be deposited on the core <NUM> using one or more processes other than those described above.

<FIG> illustrates a system <NUM> for additively manufacturing a part <NUM> (or parts) from the additive manufacturing material (e.g., powder) describe above. This additive manufacturing system <NUM> includes a support <NUM>, an additive manufacturing device <NUM> and a controller <NUM>. The additive manufacturing system <NUM> also includes a housing <NUM>, such as a sealed enclosure or pressure vessel, in which the support <NUM> and at least a portion of the additive manufacturing device <NUM> are located.

The support <NUM> includes a support surface <NUM>. This support surface <NUM> is configured to support the additive manufacturing material and/or at least a portion of the part <NUM> (or parts) during the formation of the part <NUM> (or parts). The support surface <NUM>, for example, may be substantially horizontal relative to gravity. The support surface <NUM> may also have a generally planar geometry.

The additive manufacturing device <NUM> may be configured as a cold spray device, a laser sintering device, or an electron beam melting device. Various cold spray devices, laser sintering devices and electron beam melting devices are known in the art and therefore are not described in further detail. In addition, various other types and configurations of additive manufacturing devices are known in the art and the present invention is not limited to any particular ones thereof.

The controller <NUM> is in signal communication (e.g., hardwired and/or wirelessly coupled) with the additive manufacturing device <NUM>. The controller <NUM> is adapted to signal the additive manufacturing device <NUM> to perform at least a portion of the process described below. The controller <NUM> is implemented with a combination of hardware and software. The hardware includes memory and a processing device (or system), which includes one or more single-core and/or multi-core processors. The memory may be a non-transitory computer readable medium, and configured to store software (e.g., program instructions) for execution by the processing device. The hardware may also or alternatively include analog and/or digital circuitry other than that described above.

<FIG> is a flow diagram of a process for forming a part <NUM> (or parts) using the additive manufacturing material and the additive manufacturing system <NUM>. An example of a part that may be formed with the additive manufacturing system <NUM> is a rotor blade for a turbine engine; e.g., a turbine blade, a compressor blade or a fan blade. Other examples of a part that may be formed with the additive manufacturing system <NUM> include a stator blade for a turbine engine, a guide vane for a turbine engine, a gas path wall for a turbine engine as well as various other components included in a turbine engine. The process of <FIG> and the additive manufacturing system <NUM>, of course, may also or alternatively form parts other than those included in a turbine engine.

Prior to the formation of the part <NUM> (or parts), the additive manufacturing material may be stored in an ambient environment outside of the additively manufacturing system <NUM>. Alternatively, the additive manufacturing material may be stored in a controlled environment (e.g., a vacuum or noble gas environment) and/or in a reservoir <NUM> (e.g., a hopper) of the additive manufacturing system <NUM>.

In step <NUM>, the additive manufacturing material is loaded into the additive manufacturing system <NUM>. The additive manufacturing material, for example, may be poured out or otherwise directed from its storage container into the reservoir <NUM>, which may selectively feed the material to the additive manufacturing device <NUM>.

In step <NUM>, the coating <NUM> is removed from at least some of the additive manufacturing particles (e.g., particle <NUM>) to expose the core material; e.g., the degassed metal powder cores. For example, a conduit and/or a chamber <NUM> configured with the additive manufacturing device <NUM> may be heated with a heater to or above an elevated (e.g., above ambient) temperature at which the coating material decomposes and/or volatizes. This conduit and/or chamber <NUM> may be connected upstream of a material applicator <NUM> (e.g., a powder bed nozzle or a cold spray nozzle) of the additive manufacturing device <NUM>. The material applicator <NUM> therefore may receive the exposed core material (e.g., the degassed metal powder cores) from the conduit and/or chamber <NUM>.

In step <NUM>, at least some of the exposed core material is formed into at least a portion of the part <NUM> (or parts). The material applicator <NUM>, for example, may cold spray the exposed core material onto the support surface <NUM> to build up a base layer. The material applicator <NUM> may subsequently cold spray one or more additional layers of the exposed core material onto the base layer to accumulatively form the part <NUM> (or parts). As each layer of material is cold sprayed, it may fuse to a previously sprayed layer thereby solidifying at least some of the metal powder cores <NUM> together to form the part <NUM> (or parts).

In another example, the material applicator <NUM> may deposit a uniform and compacted layer of the exposed core material onto the support surface <NUM>. A laser or electron beam energy source <NUM> may subsequently solidify (e.g., sinter or otherwise melt) some or all of the metal powder cores <NUM> in the layer together to form a base layer of the part <NUM> (or parts). The material applicator <NUM> may subsequently deposit one or more additional uniform and compacted layers of the exposed core material onto the base layer, and the laser or electron beam energy source <NUM> may respectively solidify some or all of the metal powder cores <NUM> in the additional layer(s) to form additional layers of the part <NUM> (or parts). Of course, the process of <FIG> is not limited to the foregoing exemplary material buildup techniques or devices.

One or more of the process steps of <FIG> may be omitted, re-arranged and/or combined. For example, in some embodiments, the additive manufacturing material may be stored with the additive manufacturing system <NUM>. In some embodiments, the coating <NUM> may be removed within the material applicator <NUM> and/or as the additive manufacturing particles (e.g., particle <NUM>) are directed from the material applicator <NUM> towards the support surface <NUM>. In some embodiments, the coating material may not be removed from the particles (e.g., particle <NUM>) where, for example, the coating material does not substantially affect the chemical composition and/or mechanical properties of the part <NUM> (or parts) formed therefrom.

The process of <FIG> may include one or more additional steps other than those described above. For example, in some embodiments, the part <NUM> (or parts) may undergo additional manufacturing processes during and/or after the material buildup step <NUM>. Examples of such additional manufacturing processes may include, but are not limited to, machining, surface finishing, coating, etc. In some embodiments, the part <NUM> (or parts) may also or alternatively undergo additional manufacturing processes before the material buildup step <NUM> where, for example, the additive manufacturing material is built up upon an existing part or portion of a part (or parts); e.g., to repair a part, etc..

Claim 1:
A process for forming a part (<NUM>) using an additive manufacturing system (<NUM>), the process comprising:
providing a plurality of discrete particles (<NUM>), each of the particles (<NUM>) including a metal powder core (<NUM>) encapsulated by a non-metal coating (<NUM>);
wherein the additive manufacturing system (<NUM>) comprises one of a cold spray device, a laser and an electron beam energy source, and the method further comprises:
solidifying at least some of the cores (<NUM>) together using the cold spray device, the laser or the electron beam energy source to form at least a portion of the part, wherein the solidifying comprises sintering or melting,
characterised in that the non-metal coating (<NUM>) comprises a polymer-ceramic coating.