JP7362066B2 - Titanium parts and methods for manufacturing titanium parts - Google Patents

Description

The present invention relates to a titanium member and a method for manufacturing a titanium member.

Conventionally, pure titanium and titanium alloys have been widely used as materials for aircraft and various machines because of their high strength and excellent corrosion resistance. A typical titanium alloy is, for example, the general-purpose Ti-6Al-4V (64 titanium alloy). Further, reinforced titanium produced by mixing Ti powder with _two TiB particles and sintering the mixture has also been developed (see, for example, Patent Document 1 or 2).

However, since rare metals such as V, Cr, Mo, Nb, and B are used in such titanium alloys and reinforced titanium, there is a problem in that material costs increase. Therefore, instead of these rare metals, titanium members using inexpensively available elements such as oxygen, nitrogen, and carbon are being developed (see, for example, Non-Patent Documents 1 to 5). It is known that oxygen dissolved in titanium is dispersed by heat treatment at 400° C. or 600° C. for 24 hours (for example, see Non-Patent Document 1).

Japanese Patent Application Publication No. 5-171214 Japanese Patent Application Publication No. 2001-107163

Shota Kariya, Junko Umeda, Ma Qian, Katsuyoshi Kondo, “Improvement of ductility of oxygen-added titanium material by rapid cooling treatment and elucidation of its mechanism”, Journal of the Japan Institute of Metals, October 2018, Vol. 82, No. 10, p. 390-395 Bin SUM, Shufeng Li, Hisashi Imai, Takatetsu Mimoto, Junko Umeda, Katsuyoshi Kondo, “Creation of high-strength titanium powder sintered material by solid solution strengthening with oxygen”, Smart Process Society Journal, November 2012, No. 1 Volume, No. 6, p.283-287 B. Chen, J. Shen, X. Ye, J. Umeda, K. Kondoh, “Advanced mechanical properties of powder metallurgy commercially pure titanium with a high oxygen concentration”, J. Mater. Res., 16 October 2017, Vol. 32, No. 19, p.3769-3776 S. Li, B. Sun, H. Imai, T. Mimoto, K. Kondoh, “Powder metallurgy titanium metal matrix composites reinforced with carbon nanotubes and graphite”, Composites Part A, May 2013, Vol. 48, p.57- 66 X. Zhang, F. Song, Z. Wei, W. Yang, Z. Dai, “Microstructural and mechanical characterization of in-situ TiC/Ti titanium matrix composites fabricated by graphene/Ti sintering reaction”, Mater. Sci. Eng. A, 29 September 2017, Vol. 705, p.153-159

When using a metal member such as titanium or a titanium alloy, it has the strength and ductility required depending on its use, and it is necessary to use a metal member that is suitable for the strength and ductility. With conventional titanium alloys, reinforced titanium described in Patent Documents 1 and 2, and titanium members described in Non-Patent Documents 1 to 5, it is possible to increase the strength or ductility, but the strength and ductility are There was a problem in that it was not possible to achieve both strength and ductility at relatively high values in consideration of the balance between the two.

The present invention was made with attention to such problems, and an object of the present invention is to provide a titanium member and a method for manufacturing a titanium member that can achieve both relatively high values of both strength and ductility.

In order to achieve the above object, the titanium member according to the present invention is made of titaniummosquitoIt has a structure in which oxygen atoms are diffused and TiC particles are dispersed in the matrix.However, when measured by X-ray analysis, the peaks of the titanium and the TiC appear, and each of the peaks is shifted to the high angle side.characterized by.

The method for manufacturing a titanium member according to the present invention is characterized by mixing titanium powder and cellulose nanofibers and then sintering the mixture. In the method for manufacturing a titanium member according to the present invention, titanium powder may be mixed in a dispersion of cellulose nanofibers, dried, and then the mixture may be sintered.

The method for manufacturing a titanium member according to the present invention can suitably manufacture the titanium member according to the present invention. The titanium member according to the present invention has a structure in which oxygen atoms are diffused and TiC particles are dispersed in a matrix made of titanium , so it has higher strength than a member made only of titanium or a titanium alloy. can be increased. It also has relatively high ductility, and can achieve both strength and ductility at relatively high values.

In the method for manufacturing a titanium member according to the present invention and the method for manufacturing a titanium member according to the present invention, the titanium alloy may be any alloy, such as Ti-6Al-4V (64 titanium alloy) or Ti-3Al- 2.5V alloy, Ti-6Al-2Sn-4Zr-2Mo alloy, etc.

In the titanium member according to the present invention, the matrix is preferably made of titanium and has a carbon content of 0.12 to 0.6 wt%. In the method for manufacturing a titanium member according to the present invention, it is preferable that the cellulose nanofibers are mixed in a proportion of 1.2 to 6 wt% based on the combined weight of the titanium powder and the cellulose nanofibers. In this case, both strength and/or ductility can be achieved at higher values.

In the method for manufacturing a titanium member according to the present invention, the mixture is preferably sintered at 1000° C. to 1200° C. for 30 minutes to 2 hours. In this case, it is possible to obtain a titanium member according to the present invention that has both higher strength and/or ductility.

According to the present invention, it is possible to provide a titanium member and a method for manufacturing a titanium member that can achieve both relatively high strength and ductility.

(a) Tensile test of a titanium member according to an embodiment of the present invention using titanium (Ti) powder as a raw material, (b) a titanium member according to an embodiment of the present invention using titanium alloy (64Ti) powder as a raw material. It is a stress (Tensile stress)-strain (Strain) curve showing the results. The amount of cellulose nanofibers (CNF) added and (a) Young's modulus, (b) ultimate tensile strength, ( c) It is a graph showing the relationship with fracture elongation. 1 is a stress-strain curve showing tensile test results of a titanium member, a member made of sintered pure titanium, and reinforced titanium according to an embodiment of the present invention. (a) XRD spectra showing measurement results by X-ray diffraction (XRD) method of titanium members and pure titanium sintered members according to embodiments of the present invention, (b) 2θ = 39.5° to 41 in (a) This is an XRD spectrum with an expanded range of °. (a) SEM photograph showing the observation results of the titanium member according to the embodiment of the present invention using a scanning electron microscope (SEM), (b) SEM photograph showing a part of (a) enlarged, (c) (b) (d) is an enlarged SEM photograph of a part of (c). 2A is an SEM photograph of a titanium member according to an embodiment of the present invention; FIG. Energy dispersive X-ray analysis (EDX) results of a titanium member according to an embodiment of the present invention are shown (a) SEM photograph of the analysis range, (b) elemental mapping of O, (c) elemental mapping of Ti, (d ) is the elemental mapping of C. (a) SEM photograph showing the observation results of the fractured surface of the titanium member according to the embodiment of the present invention using a scanning electron microscope (SEM) after a tensile test; (b) SEM photograph showing an enlarged part of (a) , (c) is an enlarged SEM photograph of a part of (b).

Embodiments of the present invention will be described below based on examples and the like.
The titanium member according to the embodiment of the present invention has a structure in which oxygen atoms are diffused and TiC particles are dispersed in a matrix made of titanium or a titanium alloy.

The titanium member according to the embodiment of the present invention has a structure in which oxygen atoms are diffused and TiC particles are dispersed in a matrix made of titanium or a titanium alloy, so it is different from a member made only of titanium or a titanium alloy. Comparatively, the strength can be increased. It also has relatively high ductility, and can achieve both strength and ductility at relatively high values. Note that the titanium alloy is, for example, Ti-6Al-4V (64 titanium alloy), Ti-3Al-2.5V alloy, or Ti-6Al-2Sn-4Zr-2Mo alloy.

The titanium member according to the embodiment of the present invention is suitably manufactured by the method for manufacturing a titanium member according to the embodiment of the present invention. A method for manufacturing a titanium member according to an embodiment of the present invention includes mixing titanium powder or titanium alloy powder and cellulose nanofibers and then sintering the mixture. can be manufactured.

In the method for manufacturing a titanium member according to an embodiment of the present invention, when using titanium powder, cellulose nanofibers are mixed at a ratio of 1.2 to 6 wt% with respect to the combined weight of titanium powder and cellulose nanofibers. It is preferable. When using a titanium alloy, it is preferable to mix cellulose nanofibers at a ratio of 3 wt % or less based on the combined weight of titanium alloy powder and cellulose nanofibers. Also, in order to obtain higher strength and/or ductility, the mixture is preferably sintered at 1000° C. to 1200° C. for 30 minutes to 2 hours. The sintering may be performed by any method such as a discharge plasma sintering method or a hot press method.

A titanium member was manufactured using the method for manufacturing a titanium member according to an embodiment of the present invention. First, add cellulose nanofibers (CNF) to 500 ml of water to prepare a CNF dispersion, add 50 g of titanium (pure titanium) powder or titanium alloy powder to the CNF dispersion, and use a commercially available mixer at a rotation speed of 10,000 rpm. and mixed for 1 minute. After drying the mixture, the temperature was raised to 1100°C at a rate of 50°C/min, and discharge plasma sintering was performed at 1100°C for 1 hour. After sintering, it was cooled in a furnace to obtain a titanium member.

A plurality of types of titanium members were manufactured using titanium powder and titanium alloy powder, each with a different amount of CNF. When titanium powder is used, CNF is adjusted so that the amount of CNF is 1.08 wt%, 2.16 wt%, 3.25 wt%, and 6.5 wt% with respect to the combined weight of the raw material titanium powder and CNF. A dispersion liquid was prepared, and titanium members (referred to as "Ti-1", "Ti-2", "Ti-3", and "Ti-4", respectively) were manufactured. When titanium alloy powder is used, the CNF dispersion is prepared so that the amount of CNF is 1.08 wt%, 2.16 wt%, and 3.25 wt% based on the combined weight of the raw material titanium alloy powder and CNF. and titanium members (referred to as "64Ti-1", "64Ti-2", and "64Ti-3", respectively) were manufactured. Furthermore, Ti-6Al-4V (64 titanium alloy) was used as the titanium alloy.

A tensile test was conducted on each of the obtained titanium members. Figure 1 shows the tensile stress-strain curves of each titanium member obtained from the tensile test. Figure 1(a) shows the test results of a titanium member using titanium (Ti) powder as a raw material, and as a comparative example, a member made of sintered pure titanium ("Ti" in Figure 1(a)). Test results are also shown. In addition, FIG. 1(b) shows the test results of a titanium member using titanium alloy (64Ti) powder as a raw material, and as a comparative example, a member made of sintered titanium alloy ("64Ti" ”) test results are also shown. In addition, the Young's modulus, ultimate tensile strength, and fracture elongation of each titanium member were determined from Figs. 1(a) and (b), and Figs. 2(a) to (b), respectively. Shown in c).

As shown in FIG. 1(a), it was confirmed that in a titanium member using titanium powder, the strength improved and the elongation at break decreased as the amount of CNF added increased. However, when the amount of CNF added was increased from 3.25 wt% (Ti-3) to 6.5 wt% (Ti-4), it was confirmed that the strength remained almost unchanged and only the elongation at break decreased. As shown in Figures 2(b) and (c), titanium members containing 2.16 wt% and 3.25 wt% of CNF exhibited maximum tensile strength of 600 MPa or more and elongation at break of 10% or more. It can be said that both strength and elongation at break (ductility) are relatively high and well-balanced.

Furthermore, as shown in Figure 1(b), the strength of titanium members using titanium alloy powder is slightly improved by adding CNF, but there is no tendency for the strength to improve with the amount of CNF added. There wasn't. This is considered to be because the mechanism of strengthening Ti by adding CNF is the same as the mechanism of strengthening Ti by adding elements to the alloy. It was also confirmed that the elongation at break was reduced by the addition of CNF. As shown in Figures 2(b) and (c), titanium members containing 1.08 wt% and 2.16 wt% of CNF exhibited maximum tensile strength of 800 MPa or more and elongation at break of 10% or more. It can be said that both strength and elongation at break (ductility) are relatively high and well-balanced. In addition, as shown in FIG. 2(a), it was confirmed that the Young's modulus of each titanium alloy was almost the same.

Figure 3(a) shows a titanium member (Ti-3) made by adding 3.25 wt% CNF to titanium powder, and for comparison, a member made by sintering pure titanium ("Ti-3" in Fig. 3(a)). ”) and tensile test results of reinforced titanium. There are three types of reinforced titanium: those obtained by mixing Ti powder with ₂ TiB particles at 1 vol%, 5 vol%, and 10 vol%, respectively, and sintering them (respectively, "TiB-" in Figure 3(a)). 1'', ``TiB-2'', ``TiB-3''). As shown in Figure 3(a), the only titanium member with an elongation at break of 10% or more and excellent strength is the titanium member with 3.25 wt% of CNF added. It can be seen that both properties (ductility) are achieved at relatively high values.

Using a thermogravimetric/differential thermal analysis (TG-DTA) device, thermogravimetry (TG) was measured when CNF was heated. The measurement results are shown in FIG. 3(b). As shown in FIG. 3(b), it was confirmed that the weight of CNF decreased by approximately one-tenth during heating from room temperature to 1000°C. From this, it is considered that in each manufactured titanium member, the weight of CNF added before sintering is reduced to about 1/10 after sintering. Therefore, for example, in each titanium member manufactured by adding 1.08 wt%, 2.16 wt%, 3.25 wt%, and 6.5 wt% of CNF, the weight of carbon is approximately 0.108 wt% and approximately 0. It is thought that they are about .216 wt%, about 0.325 wt%, and about 0.65 wt%.

Next, a titanium member (Ti-3) made by adding 3.25 wt% CNF to titanium powder was subjected to measurements using X-ray diffraction (XRD), observation using a scanning electron microscope (SEM), and energy-dispersive X-ray Analysis (EDX) was performed. The measurement results by the X-ray diffraction (XRD) method are shown in FIG. For comparison, FIG. 4 also shows the measurement results of a member made of sintered pure titanium ("Ti" in FIG. 4). As shown in FIG. 4, peaks of Ti and TiC were confirmed. Furthermore, it was confirmed that each peak was shifted to the right by adding CNF.

The results of observation using a scanning electron microscope (SEM) are shown in FIGS. 5(a) to 5(d). As shown in Figures 5(a) to (d), the matrix portion (the light gray area in the figure; for example, the portion A in Figures 5(b) and (c)) and the particles dispersed in the matrix. (the dark gray part in the figure; for example, the part B in Figure 5(b)), the grain boundary (for example, the part C in Figures 5(c) and (d)), and the cavity part (the part B in Figure 5(c) and (d)). The black part inside (for example, part D in FIG. 5(d)) was confirmed. Note that the slightly dark gray portion in the figure (for example, the portion E in FIG. 5(a)) is considered to be the strain generated by polishing during preparation of the sample for SEM observation.

The results of energy dispersive X-ray analysis (EDX) performed on the matrix portion and the particulate portions dispersed in the matrix are shown in FIGS. 6 and 7, respectively. As shown in FIG. 6, it was confirmed that Ti was widely distributed in the matrix portion, but C and O were also present. From this result, it is considered that C and O are diffused into the pure titanium matrix.

As shown in FIG. 7, it was confirmed that C, O, and Ti were present in the particulate portion. It was also confirmed that this particulate portion had rounded corners (for example, portion _B1 in FIG. 5(d)). From these results, it is considered that the particulate portions are hard TiC particles using CNF as a precursor. In addition, the vicinity of this particulate part (for example, part _B2 in Figure 5(c)) shows a slightly dark gray color, indicating that C and O are diffused here at a high concentration. it is conceivable that. From this result, in conventional titanium or titanium alloys with carbon added (for example, see Non-Patent Documents 4 or 5), the strength is increased by dispersing TiC particles, but the titanium member of the embodiment of the present invention It is thought that not only the dispersion of TiC particles but also the diffusion of oxygen atoms contributes to the improvement in strength.

The results of scanning electron microscopy (SEM) observation of the fractured surface after the tensile test are shown in FIGS. 8(a) to 8(c). As shown in FIGS. 8(a) to (c), TiC particles using CNF as a precursor were confirmed (for example, the portion F in FIG. 8(b)). In addition, a dimple-like fracture surface shape that appears during ductile fracture was also confirmed (for example, the part G in Fig. 8(c)), which suggests that this titanium member has excellent elongation at break. I can say that.

Claims (5)

It has a structure in which oxygen atoms are diffused and TiC particles are dispersed in a matrix made of titanium ,
A titanium member characterized in that, when measured by X-ray analysis, peaks of the titanium and the TiC appear, and each of the peaks is shifted to a higher angle side. After mixing titanium powder and cellulose nanofibers, the mixture is sintered, and a matrix consisting of titanium has a structure in which oxygen atoms are diffused and TiC particles are dispersed, which is measured by X-ray analysis. A method for manufacturing a titanium member , characterized in that, when doing so, peaks of the titanium and the TiC appear, and a titanium member is obtained in which each of the peaks shifts to a higher angle side. Titanium powder is mixed in a dispersion of cellulose nanofibers, dried, and then the mixture is sintered to create a matrix made of titanium that has a structure in which oxygen atoms are diffused and TiC particles are dispersed. A method for manufacturing a titanium member, characterized in that a titanium member is obtained in which peaks of the titanium and the TiC appear and each of the peaks shifts to a higher angle side when measured by X-ray analysis. The method for manufacturing a titanium member according to claim 2 or 3 , characterized in that the cellulose nanofibers are mixed at a ratio of 1.2 to 6 wt% with respect to the combined weight of the titanium powder and the cellulose nanofibers. . The method for manufacturing a titanium member according to any one of claims 2 to 4, characterized in that the mixture is sintered at 1000° C. to 1200° C. for 30 minutes to 2 hours.