Preparation and Characterization of Low Temperature Sintered Alumina by CuO-TiO 2 -Nb 2 O 5 -Ag 2 O Additives

Trans. Mat. Res. Soc. Japan

Asakawa

Kuraoka

et al. 2016

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Recent studies by the authors have been intended to develop sintering additives that can make alumina sintered at low temperature with a small quantity. In the case of use of CuO-TiO 2-Nb 2 O 5-Ag 2 O type additives, high-density alumina was obtained by firing at a temperature of 900℃ or below, even though additives content was only 5mass%. In this study, co-firing of above materials with Ag-electrodes at 900℃ or below was examined in order to clarify the relationship between chemical compositions and their reactivity. The results showed that reactivity was highly affected by the Ag 2 O content in the sintering additives. When the content of Ag 2 O was higher, any disappearance of Ag-electrodes was not found and electric properties were almost the same as those of conventional LTCC materials. Finally, these results indicated the obtained materials had possibility to be applied to LTCC modules having high thermal conductivity.

Section: Fig5 Photos Of Boundary Between Ag Electrode and Lowmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Effects of Chemical Compositions on Electrical Properties of Low Temperature Co-fired Alumina Ceramics with Built-in Silver Electrodes

Trans. Mat. Res. Soc. Japan

Asakawa

Kuraoka

et al. 2016

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“…For additive-free samples, needle-like TiO2 particles (FTL-300, Ishihara Sangyo Co., Ltd.), which are elongated along the c-axis, were pulverized in a ball mill for 0, 6, 24, and 72 h and dried. For preparing samples with sintering additives, 95 mass% of the TiO2 particles were mixed with 5 mass% of CuO-TiO2-Nb2O5-Ag2O type oxides, which were found to be effective in sintering of the alumina at low temperatures according to our previous studies [9][10]. The mixture was pulverized for 6 h. Subsequently, oriented ceramics were fabricated using the above-mentioned OCAP method.…”

Section: Methodsmentioning

confidence: 99%

Improvement of Sintering Performances and Dielectric Properties of Oriented TiO2 Ceramics Using Sintering Additives

Trans. Mat. Res. Soc. Japan

Fujimori

2016

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We successfully examined effects of pulverization and an addition of sintering aids on the orientation degree, sintering performances, and dielectric properties of sintered compacts of needle-like TiO 2 particles. In the case of additive-free samples, an improvement in sintering performances was achieved by pulverization. However, the orientation degrees of these samples were decreased and calcination at high temperatures (≥ 1200 °C) was indispensable for obtaining an adequate relative density. On the other hand, by the addition of CuO-TiO 2-Nb 2 O 5-Ag 2 O type additives, the samples could be well sintered as much as 380 °C below their original sintering temperature with retaining the high orientation degrees. Moreover, high insulation resistances were achieved for samples with additives compared to that of additive-free samples and its relationship with the microstructures was discussed. Thus, this study provides an experimental investigation on improvements of sinterabilities and insulation properties of orientated TiO 2 ceramics by the use of sintering additives.

“…[10][11][12][13][14] However, none of these binary composition samples have been shown to exhibit satisfactory sintering performance at temperatures below 1000°C. 17 Co-firing of the aforementioned materials with Ag electrodes at 900°C or below was previously examined to clarify the relationship between chemical compositions and their reactivity. 15,16 Furthermore, through the use of a CuO-TiO 2 -Nb 2 O 5 -Ag 2 O additive, which is obtained by adding Ag 2 O to the CuO-TiO 2 -Nb 2 O 5 additive, further low-temperature sintering of alumina has been realized.…”

Section: Introductionmentioning

confidence: 99%

“…A previous study showed that the obtained material exhibited high thermal conductivity of 18 W/mK, exceeding the values of conventional LTCC materials. 17 Co-firing of the aforementioned materials with Ag electrodes at 900°C or below was previously examined to clarify the relationship between chemical compositions and their reactivity. Results showed that reactivity was highly affected by the Ag 2 O content in the sintering additives.…”

Section: Introductionmentioning

confidence: 99%

Examination of non‐shrinkage firing using low‐temperature co‐fired alumina containing a small quantity of Cu–Ti–Nb–Ag–O additive

Int J Applied Ceramic Tech

Tezuka

2019

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In this study, we examined non‐shrinkage firing in the planar direction using low‐temperature co‐fired alumina (LTCA) containing a small quantity of Cu–Ti–Nb–Ag–O additive. A good restraint effect was obtained using AL‐43‐L alumina as a constraint layer whose particle diameter was several times larger (1 to 2 μm) than that of alumina in the LTCA material TM‐5D (0.2 μm). The x‐y shrinkage ratio of the non‐shrinkage fired sample using AL‐43‐L as the constraint layer was within 2 %. However, the density of the non‐shrinkage fired sample was much lower than that of the normal shrinkage fired sample. By producing a powder using a freeze‐dry method, we obtained a well‐sintered alumina with a relative density of approximately 95 % at 950°C, which is lower than the melting point of silver. That is, we achieved both suppression of the shrinkage rate in the x‐y direction and ensured sinterability below the melting point of silver. The thermal conductivity of the sample was 16.2 W/mK, which is extremely high for low‐temperature co‐fired ceramics materials.