⑨去成江工大雪 国去成工大雪 3、典型实例分析 DTG曲线上的A点表示 了TG曲线上的最大失 1 Step CaC2O H2O (s)CaC2O,(s)+H2O (g) 重率的值。通过DTG曲 线既能够知道试样的 Calcumxalate Monohydrate Cafclum xaate TG曲线上各点质量的 变化速率，同时还能知 2nd Step CaC2O (s)(s)+CO (g) 道TG曲线下降段转折 点的温度值。 3d Step 图安孩谨工大雪 图支藏理工大坐 Alomic Masses Overlay of runs.same conditions H=1007 c=120 0=15.99 Ca=40.06 MwofCaC,0,H,0=146064 bon monoxide mass loss=28/146.064=19% Theoretical carbon dioxide mass loss =43.99/146.064=30.2% 国支藏谨工大当 ©去灰理江大等 of the sample and how you positiontn the pan Perform multiple runs cnough to do a statistical analysis up repeat the CaleiumDTG A TG DTG TG TG 3 1st Step CaC2O4•H2O (s) CaC2O4 (s) + H2O (g) Calcium Oxalate Monohydrate Calcium Oxalate 2nd Step CaC2O4 (s) CaCO3 (s) + CO (g) Calcium Oxalate Calcium Carbonate 3rd Step CaCO3 (s) CaO (s) + CO2 (g) Calcium Carbonate Calcium Oxide Atomic Masses: H = 1.007 C = 12.01 O = 15.99 Ca = 40.06 Mw of CaC2O4•H2O = 146.064 Theoretical % water mass loss = 18.004/146.064 = 12.3% Theoretical % carbon monoxide mass loss = 28/146.064 = 19.2% Theoretical % carbon dioxide mass loss = 43.99/146.064 = 30.2% 0.0 0.6 [ ––––––– ] Deriv. Weight (%/°C) 20 40 60 80 100 Weight (%) 0 200 400 600 800 Temperature (°C) Overlay of 8 runs, same conditions ★ Although Calcium Oxalate is not generally accepted as a “Standard Material,” it does have practical utility for INTRA￾laboratory use ★ Carefully control the experimental conditions; i.e. pan type, purge gases/flow rates, heating rate ★ Particularly control the amount (~5mg) and the particle size of the sample and how you position it in the pan ★ Perform multiple runs, enough to do a statistical analysis ★ Analyze the weight changes and peak temperatures and establish the performance of YOU and YOUR instrument ★ When performance issues come up, repeat the Calcium Oxalate analysis 13.08% 19.04% 30.14% -0.2 -0.1 0.0 0.1 Temperature Difference (°C/mg) -2 0 2 4 6 8 10 Deriv. Weight (%/min) 20 40 60 80 100 120 Weight (%) 0 200 400 600 800 1000 Temperature (°C) Sample: Calcium Oxalate Size: 13.2324 mg Method: RT-->1000°C @ 20°C/min Comment: N2 Purge=100mL/min TGA-DTA File: C:\TA\Data\SDT\SDT-CAOX.001 Operator: Applications Laboratory Run Date: 10-May-1995 08:07 Exo Up Universal V4.3A TA Instruments