# US 11,280,007 B2 · Chemical process for matification

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- Number: US 11,280,007 B2
- Document ID: US11280007B2
- Status: Granted
- Kind: B2
- Application number: 16/664,461
- Filed: 2019-10-25
- Published: 2020-04-30
- Granted: 2022-03-22
- Earliest claimed: 2018-10-26
- Assignees: Safran Aircraft Engines
- Applicants: Safran Aircraft Engines
- Inventors: Pierre-Joseph Xavier Hervé Saget
- Web page: https://patentgrep.com/patent/US11280007B2

## CPC

- C23F 1/26: for etching refractory metals
- C23G 1/106: {refractory metals}
- F01D 25/002: {Cleaning of turbomachines}
- C23G 1/14: with alkaline solutions
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)

## Abstract

The invention relates to a method for mattifying a turbine engine part (10) comprising a metal material, the method comprising a step of immersing said part in a chemical bath (14) for mattifying said metal part (10), the bath (14) comprising at least sodium fluoride (NaF) and hydrofluoric (HF) acid, characterised in that the immersion step lasts between 2 and 15 minutes.

## Claims

### Claim 1

A method of mapping a turbine engine part comprising a metal material, the method comprising the following steps:
a step of preparing a surface of the at least one part comprising:
a step of degreasing the part for 10 minutes at a temperature of between 45 and 55° C., during which the tool is immersed in an alkaline bath;
a first step of passive rinsing of 60 seconds at ambient temperature, during which the tool is immersed in a water bath; and
a second step of current rinsing of 120 seconds at ambient temperature, during which the tool is immersed in a running water bath or water-sprayed;
following the step of preparing the surface, mattifying the part by immersing said part in a chemical bath for mattifying said metal material, the chemical bath comprising at least sodium fluoride (NaF) and hydrofluoric (HF) acid, that wherein the immersion step lasts between 2 and 15 minutes; and
measuring by a contactless method a parameter of the part to establish a mapping.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the immersion step provides a homogenous dissolution of the metal material over a thickness of around 3 to 10 μm.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the metal material of the part comprises titanium (Ti), a titanium alloy and/or titanium oxides (TiO2).

### Claim 4 (depends on 1)

The method according to claim 1, wherein the immersion step leads to a dissolution of the metal material of the part over a thickness of 5 μm.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the part is enriched with dihydrogen (H2) and in that the enriching with dihydrogen (H2) of the part is around 15 ppm.

### Claim 6 (depends on 2)

The method according to claim 2, wherein the part has, on the surface, a titanium oxide (TiO2) and alpha case layer, the homogenous dissolution making it possible to remove the titanium oxide (TiO2) and alpha case layer.

### Claim 7 (depends on 1)

The method according to claim 1, it comprises further comprising a step of installing at least one part to be mattified in a tool prior to the step of immersing in the chemical bath.

### Claim 8 (depends on 7)

The method according to claim 7, wherein the temperature of the chemical bath during the immersion step is of between 15 and 30° C.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the concentration of sodium fluoride (NaF) is from 11 g to 15 g per litre of bath and wherein the bath further comprises sulphuric acid (H2SO4) at a concentration of 75+/−5 mL per litre of bath, the remaining being completed with water (H2O).

### Claim 10

A method of mapping a turbine engine part comprising a metal material, the method comprising the following steps:
a step of preparing the surface of the at least one part comprising:
a step of degreasing the part for 10 minutes at a temperature of between 45 and 55° C., during which the tool is immersed in an alkaline bath;
a first step of passive rinsing of 60 seconds at ambient temperature, during which the tool is immersed in a water bath; and
a second step of current rinsing of 120 seconds at ambient temperature, during which the tool is immersed in a running water bath or water-sprayed;
following the step of preparing the surface, mattifying the part by immersing said part in a chemical bath for mattifying said metal material, the chemical bath comprising at least sodium fluoride (NaF) and hydrofluoric (HF) acid, the immersion step lasting between 2 and 15 minutes, and the chemical bath further comprising sulphuric acid (H2SO4) and water (H2O), wherein the homogenous dissolution occurs successively and/or at the same time according to two of the following chemical reactions:
NaF+H2SO4═FH+NaHSO4 (1)
TiO2+6HF→TiF6H2+H2O; and (2)
measuring by a contactless method a parameter of the part to establish a mapping.

### Claim 11

A method of mapping a turbine engine part comprising a metal material, the method comprising:
installing said part in a tool;
immersing said part in a chemical bath for mattifying said metal material, the chemical bath comprising sodium fluoride (NaF) and hydrofluoric (HF) acid, wherein the immersion step lasts between 2 and 15 minutes;
rinsing the part, carried out after the immersing, and comprising:
a passive rinsing step of 60 seconds at ambient temperature, during which the tool is immersed in a water bath;
a current rinsing step of 120 seconds at ambient temperature, during which the tool is immersed in a running water bath or water-sprayed; and
a final hot rinsing step of 45 seconds at a temperature greater than or equal to 70° C., during which the tool is immersed in a running water bath or water-sprayed; and
measuring by a contactless method a parameter of the part to establish a mapping.

### Claim 12 (depends on 11)

The method according to claim 11, wherein the metal material of the part comprises titanium (Ti), a titanium alloy and/or titanium oxides (TiO2).

### Claim 13 (depends on 11)

The method according to claim 11, wherein the immersion step leads to a dissolution of the metal material of the part over a thickness of 5 μm.

### Claim 14 (depends on 11)

The method according to claim 11, wherein the part is enriched with dihydrogen (H2) and in that the enriching with dihydrogen (H2) of the part is around 15 ppm.

### Claim 15 (depends on 11)

The method according to claim 11, wherein the immersion step provides a homogenous dissolution of the metal material over a thickness of around 3 to 10 μm.

### Claim 16 (depends on 15)

The method according to claim 15, wherein the part has, on the surface, a titanium oxide (TiO2) and alpha case layer, the homogenous dissolution making it possible to remove the titanium oxide (TiO2) and alpha case layer.

### Claim 17 (depends on 16)

The method according to claim 16, wherein the chemical bath further comprises sulphuric acid (H2SO4) and water (H2O) and wherein the homogenous dissolution occurs successively and/or at the same time according to two of the following chemical reactions:
NaF+H2SO4═FH+NaHSO4 (1)
TiO2+6HF→TiF6H2+H2O (2)

### Claim 18 (depends on 11)

The method according to claim 11, further comprising a step of installing at least one part to be mattified in a tool prior to the step of immersing in the chemical bath.

### Claim 19 (depends on 18)

The method according to claim 18, wherein the temperature of the chemical bath during the immersion step is of between 15 and 30° C.

### Claim 20 (depends on 11)

The method according to claim 11, wherein the concentration of sodium fluoride (NaF) is from 11 g to 15 g per litre of bath and wherein the bath further comprises sulphuric acid (H2SO4) at a concentration of 75+/−5 mL per litre of bath, the remaining being completed with water (H2O).